epidermal-growth-factor and Hypertension

Members of the epidermal growth factor (EGF)-family bind to ErbB (EGFR)-family receptors that play an important role in the regulation of various fundamental cell processes in many organs including the kidney. In this field, most of the research efforts are focused on the role of EGF-ErbB axis in cancer biology. However, many studies indicate that abnormal ErbB-mediated signaling pathways are critical in the development of renal and cardiovascular pathologies. The kidney is a major site of the EGF-family ligands synthesis, and it has been shown to express all four members of the ErbB receptor family. The study of kidney disease regulation by ErbB receptor ligands has expanded considerably in recent years. In vitro and in vivo studies have provided direct evidence of the role of ErbB signaling in the kidney. Recent advances in the understanding of how the proteins in the EGF-family regulate sodium transport and development of hypertension are specifically discussed here. Collectively, these results suggest that EGF-ErbB signaling pathways could be major determinants in the progress of renal lesions, including its effects on the regulation of sodium reabsorption in collecting ducts.

Topics: Absorption; Animals; Blood Pressure; Epidermal Growth Factor; ErbB Receptors; Humans; Hypertension; Kidney; Kidney Tubules, Collecting; Ligands; Risk Factors; Signal Transduction; Sodium; Sodium Chloride, Dietary

Hypertension is characterized by a sustained increase in vasoconstriction and attenuated vasodilation in the face of elevated mechanical stress in the blood vessel wall. To adapt to the increased stress, the vascular smooth muscle cell and its surrounding environment undergo structural and functional changes known as vascular remodeling. Multiple mechanisms underlie the remodeling process, including increased expression of humoral factors and their receptors as well as adhesion molecules and their receptors, all of which appear to collaborate and interact in the response to pressure elevation. In this review, we focus on the interactions between integrin signaling pathways and the activation of growth factor receptors in the response to the increased mechanical stress experienced by blood vessels in hypertension.

Topics: Biomechanical Phenomena; Calcium Channels; Endothelium, Vascular; Epidermal Growth Factor; ErbB Receptors; Extracellular Matrix; Humans; Hypertension; Insulin-Like Growth Factor I; Integrins; Mechanical Phenomena; Muscle, Smooth, Vascular; Receptor, Angiotensin, Type 1; Signal Transduction

Extensive evidence indicates that receptor tyrosine kinases and nonreceptor tyrosine kinases underlie vascular damage in hypertension. However, recent clinical studies using vascular endothelial growth factor (VEGF) receptor inhibitors (bevacizumab, axitinib) revealed the unexpected finding of increased blood pressure. Whether this is a generalized receptor tyrosine kinase phenomenon or a VEGF receptor-specific effect is unclear. The present review focuses on current findings regarding the role of tyrosine kinases and signaling in vascular pathobiology of hypertension.. Multiple complex and interacting signaling pathways activated by receptor and nonreceptor tyrosine kinases are upregulated and have been implicated in vascular alterations associated with high blood pressure. Experimental evidence suggests that receptor tyrosine kinase activation by direct ligand binding as well as by ligand-independent mechanisms through transactivation by G protein-coupled receptors plays a role in vascular signaling and cardiovascular diseases.. Cellular mechanisms and signaling pathways mediated by tyrosine kinases involved in hypertensive vascular damage are currently the subject of intensive investigation. The unexpected finding of hypertension as a side effect in patients treated with VEGF receptor inhibitors suggests that some tyrosine kinases negatively regulate vascular function. Further characterization of these processes will provide greater understanding of the role of tyrosine kinases in vascular pathobiology in hypertension and should provide new insights on novel therapeutic targets.

Topics: Animals; Blood Vessels; Epidermal Growth Factor; Humans; Hypertension; Insulin-Like Growth Factor I; Platelet-Derived Growth Factor; Protein-Tyrosine Kinases; Receptor Protein-Tyrosine Kinases; Vascular Endothelial Growth Factor A

This rare ulcer was treated with a human recombinant epidermal growth factor-based formulation and antihypertensive drugs. Full granulation was achieved in 49 days and complete wound closure in 79 days. No adverse events were reported.

Topics: Aged; Chemistry, Pharmaceutical; Debridement; Epidermal Growth Factor; Female; Granulation Tissue; Humans; Hypertension; Leg Ulcer; Rare Diseases; Treatment Outcome; Wound Healing

Agonist stimulation of certain G protein-coupled receptors (GPCRs) causes shedding of heparin-binding epidermal growth factor (HB-EGF) through activation of matrix metalloproteinases (MMPs), with subsequent transactivation of the EGF receptor. MMPs are widely expressed, and their dysregulated expression is crucial in cancer, inflammation, and cardiovascular remodeling. Recent studies in hypertensive animals have shown enhanced expression and activation of MMPs and EGF receptors, and their inhibition attenuates cardiac hypertrophy, vasoconstriction and hypertension induced by GPCR agonists such as angiotensin II, endothelin-1 and phenylepherine. These findings suggest that selective inhibition of MMPs might have therapeutic potential in hypertension and other cardiovascular diseases.

Topics: Animals; Epidermal Growth Factor; ErbB Receptors; Heparin; Heparin-binding EGF-like Growth Factor; Hypertension; Hypertrophy, Left Ventricular; Intercellular Signaling Peptides and Proteins; Matrix Metalloproteinases; Myocardium; Rats; Receptors, G-Protein-Coupled; Signal Transduction; Transcriptional Activation

Topics: Adult; Aged; Aging; Alcoholism; Amino Acids; Anesthetics, Local; Animals; Anti-Infective Agents; Anti-Inflammatory Agents; Aqueous Humor; Autonomic Nervous System; Biological Transport, Active; Brain Chemistry; Cardiac Glycosides; Catecholamines; Cell Differentiation; Central Nervous System; Diabetes Mellitus, Type 1; Diabetic Retinopathy; Epidermal Growth Factor; Eye; Fibrinolysis; Glaucoma; Granuloma; Graves Disease; Hallucinogens; Humans; Hypertension; Immunity, Cellular; Infant; Infant, Newborn; Leukotriene B4; Metabolism, Inborn Errors; Multiple Sclerosis; Muscle Relaxation; Nutritional Physiological Phenomena; Oxygen; Oxygen Consumption; Pigment Epithelium of Eye; Pineal Gland; Prostaglandin Antagonists; Prostaglandins; Psychotropic Drugs; Retina; Retinal Degeneration; Serotonin; Smoking; SRS-A; Stress, Physiological; Water-Electrolyte Balance

To compare the effect of the antihypertensive drugs nitrendipine and enalapril on the excretion of epidermal growth factor (EGF) and albumin in hypertensive non-insulin-dependent diabetes mellitus (NIDDM) subjects.. After a 4-week washout period, mildly hypertensive (systolic blood pressure [sBP] > or = 140 mmHg and/or diastolic blood pressure [dBP] > or = 90 mmHg) NIDDM patients with albuminuria (15-200 micrograms/min) were randomized into an 8-month-long therapy with either nitrendipine (n = 11) or enalapril (n = 10). Blood pressure, EGF, and microalbumin excretion were measured at baseline and throughout the treatment period.. A significant fall in sBP was noticed in the enalapril group and in dBP in the nitrendipine group. In the enalapril group, EGF excretion progressively increased from 188 to 214 nmol/mmol creatinine after 6 weeks and to 274 after 8 months of therapy (P = 0.03). There was a significant fall in albumin excretion while patients were on enalapril, but in the nitrendipine group, neither albuminuria nor EGF excretion changed significantly. There was no correlation of improved EGF excretion with a decrease in albuminuria or BP.. The angiotensin-converting enzyme inhibitor enalapril has been effective in decreasing albumin and increasing EGF excretion. Measurement of urinary EGF may provide a new valuable index of renal function.

Topics: Adult; Aged; Albuminuria; Angiotensin-Converting Enzyme Inhibitors; Antihypertensive Agents; Biomarkers; Blood Pressure; Creatinine; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Enalapril; Epidermal Growth Factor; Humans; Hypertension; Middle Aged; Nitrendipine

Urine biomarkers of kidney tubule injury associate with incident hypertension in older adults with comorbidities, but less is known about these associations in younger adults.. In 1170 participants of the CARDIA study (Coronary Artery Risk Development in Young Adults; mean age, 45 years; 40% Black people; 56% women) without hypertension, cardiovascular disease, or kidney disease at baseline, we examined associations of urine MCP-1 (monocyte chemoattractant protein-1), α1m (alpha-1-microglobulin), KIM-1 (kidney injury molecule-1), EGF (epidermal growth factor), IL (interleukin)-18, YKL-40 (chitinase-3-like protein 1), and UMOD (uromodulin) with incident hypertension (onset of systolic blood pressure [BP] ≥130 mm Hg or diastolic BP ≥80 mm Hg or initiation of hypertension medications) and longitudinal BP change in models adjusted for hypertension risk factors, estimated glomerular filtration rate, and albuminuria.. After a median 9.9 (interquartile range, 5.9-10.2) years, 376 participants developed incident hypertension. In demographic-adjusted analyses, higher tertiles of EGF associated with lower risk of incident hypertension in both Black and White participants. After multivariable adjustment, the risk of incident hypertension remained lower in tertile 2 (hazard ratio, 0.70 [95% CI, 0.50-0.97]) and tertile 3 (hazard ratio, 0.58 [0.39-0.85]) of EGF versus tertile 1. In fully adjusted models, participants in EGF tertile 3 had smaller 10-year increases in systolic (-3.4 [95% CI, -6.1 to -0.7] mm Hg) and diastolic BP (-2.6 [95% CI, -4.6 to -0.6] mm Hg) than tertile 1. Other biomarkers showed inconsistent associations with incident hypertension and BP change.. In middle-aged adults without hypertension, cardiovascular disease, or kidney disease, higher urine EGF associated with lower risk of incident hypertension and lower 10-year BP elevations.

Topics: Aged; Biomarkers; Blood Pressure; Cardiovascular Diseases; Epidermal Growth Factor; Female; Glomerular Filtration Rate; Humans; Hypertension; Hypotension; Kidney Diseases; Kidney Tubules; Male; Middle Aged; Risk Factors; Young Adult

Topics: Cyclic Nucleotide Phosphodiesterases, Type 3; Epidermal Growth Factor; ErbB Receptors; Humans; Hypertension; Kidney

Hypertension and hyperuricemia are closely associated with an intermingled cause and effect relationship. Additionally, urinary sodium and potassium excretion is related to blood pressure. Whether or not it is associated with urinary uric acid excretion is not clear. Therefore, we aim to study the association of urinary sodium and potassium with renal uric acid excretion in patients with CKD.. A cross-sectional study of 428 patients with CKD recruited from our department was conducted. All patients were divided into hypertension and non-hypertension group. In these two groups, Spearman correlation and multiple linear regression analysis were used to study the correlation of urinary sodium and potassium with renal handling of uric acid.. According to multiple linear regression analysis, in hypertension group, fractional excretion of sodium (FEna) was negatively correlated with 24 hour urinary uric acid (24-hUur) and uric acid clearance rate (Cur) (beta coefficients [B]=-0.066, -0.182, respectively; both P< 0.05), and positively correlated with fractional excretion of uric acid (FEur) (B=1.641, P< 0.001). Additionally, fractional excretion of potassium (FEk) was positively correlated with FEur (B=0.576, P< 0.001), but not related to 24-hUur and Cur (both P>0.05). And urinary sodium/potassium ratio (Una/k) was negatively related to 24-h Uur and Cur (B=-0.047, -0.159, both P< 0.05), and positively related to FEur (B=0.578, P< 0.05). Furthermore, FEna and FEk was still positively related to FEur in the lowest tertile of eGFR groups (both P< 0.05), but not related in the second and highest tertile of eGFR groups (all P> 0.05). In non-hypertension group, FEna was negatively correlated with 24-hUur (B=-0.589, P< 0.05), but not related to Cur and FEur (both P> 0.05). both FEk and Una/k was not related to 24-h Uur, Cur and FEur (all P> 0.05). Moreover, FEna and FEk was still not correlated with FEur in all tertiles of eGFR groups (all P> 0.05).. We found that in patients with CKD, urinary sodium and potassium excretion is closely correlated to renal handling of uric acid, which was pronounced in hypertensive patients with low eGFR. This phenomenon may be one of the mechanisms of the relationship between hypertension and hyperuricemia. Further research is needed to confirm it. It is expected to manage hyperuricemia in terms of controlling the diet of sodium and potassium.

Topics: Adult; Aged; Cross-Sectional Studies; Epidermal Growth Factor; Female; Humans; Hypertension; Hyperuricemia; Linear Models; Male; Middle Aged; Potassium; Renal Insufficiency, Chronic; Sodium; Uric Acid

Juxtaglomerular cell tumor (JGCT) is a rare tumor, with approximately 100 cases reported in the literature. The authors respectively studied the clinical data of 11 patients diagnosed with JGCT in Peking Union Medical College Hospital from 2004 to 2014, and investigated the immunohistochemical profiles in 10 tumors. Nine of the 11 patients were diagnosed before the age of 40 years. Hypertension was present in all patients, while hypokalemia occurred in seven of 11 patients. Computed tomography detected JGCTs with a sensitivity of 100%. Immunoreactivities for CD34 and vascular endothelial growth factor were observed in most tumor specimens, suggesting that JGCTs express a variety of vessel-related immunohistochemical markers, although JGCTs are considered a tumor without abundant blood supply. Nuclear accumulation of cyclin D1 was common in JGCTs. Results from immunohistochemistry were negative for BRAF, HER2, and TFE3, suggesting that BRAF, HER2, and TFE3 genes might not play a part in tumorigenesis in JGCTs.

Topics: Adolescent; Adult; Aged; Antigens, CD34; Child; Comorbidity; Epidermal Growth Factor; Female; Humans; Hypertension; Hypokalemia; Juxtaglomerular Apparatus; Kidney Neoplasms; Male; Middle Aged; Retrospective Studies; Tomography, X-Ray Computed; Young Adult

Platelet activation might play a significant role in the pathophysiology of cardiovascular and cerebrovascular events in hypertension (HT). Signal peptide-CUB-EGF domain-containing protein1 (SCUBE1), an indicator of platelet activation, is increased in HT. The aim of this study was to investigate the SCUBE1 in patients with hypertensive crises.. This study included 33 hypertensive urgency (HU) and 39 hypertensive emergency (HI) patients admitted to our emergency department with a diagnosis of hypertensive crisis. Platelet activation was evaluated with biochemical markers such as SCUBE1, soluble CD40L (sCD40L), mean platelet volume, and platelet count.. The SCUBE1 values of the HE patients were significantly higher than other groups (1.09 ± 0.49, 0.71 ± 0.23 and 0.37 ± 0.02 ng/dl, respectively; p <  0.01). The sCD40L values were higher in the hypertensive crises compared with the control group (4.16 ± 1.82, 3.41 ± 1.76 and 1.76 ± 0.68 ng/ml, respectively; p <  0.01). More importantly, SCUBE1 had high sensitivity and specificity in the detection of target organ damage.. In present study showed that SCUBE1 was significantly higher in HE patients. In addition, sCD40L level, presence of diabetes, and systolic blood pressure were independently associated with increased SCUBE1. According to our results, SCUBE1 might be a diagnostic biomarker in hypertensive crisis patients.

Topics: Aged; Biomarkers; Epidermal Growth Factor; Female; Humans; Hypertension; Male; Mean Platelet Volume; Middle Aged; Platelet Activation; Protein Sorting Signals

Proliferation and hypertrophy of vascular smooth muscle cells represent hallmark features of vessel remodeling secondary to hypertension. The intermediate filament protein nestin was recently identified in vascular smooth muscle cells and in other cell types directly participated in proliferation. The present study tested the hypothesis that vessel remodeling secondary to hypertension was characterized by nestin upregulation in vascular smooth muscle cells. Two weeks after suprarenal abdominal aorta constriction of adult male Sprague-Dawley rats, elevated mean arterial pressure increased the media area and thickness of the carotid artery and aorta and concomitantly upregulated nestin protein levels. In the normal adult rat carotid artery, nestin immunoreactivity was observed in a subpopulation of vascular smooth muscle cells, and the density significantly increased following suprarenal abdominal aorta constriction. Filamentous nestin was detected in cultured rat carotid artery- and aorta-derived vascular smooth muscle cells and an analogous paradigm observed in human aorta-derived vascular smooth muscle cells. ANG II and EGF treatment of vascular smooth muscle cells stimulated DNA and protein synthesis and increased nestin protein levels. Lentiviral short-hairpin RNA-mediated nestin depletion of carotid artery-derived vascular smooth muscle cells inhibited peptide growth factor-stimulated DNA synthesis, whereas protein synthesis remained intact. These data have demonstrated that vessel remodeling secondary to hypertension was characterized in part by nestin upregulation in vascular smooth muscle cells. The selective role of nestin in peptide growth factor-stimulated DNA synthesis has revealed that the proliferative and hypertrophic responses of vascular smooth muscle cells were mediated by divergent signaling events.

Topics: Angiotensin II; Animals; Aorta; Carotid Arteries; Cells, Cultured; DNA Replication; Epidermal Growth Factor; Hypertension; Male; Muscle, Smooth, Vascular; Nestin; Rats; Rats, Sprague-Dawley; Up-Regulation; Vascular Remodeling

An increased risk for developing essential hypertension, stroke and diabetes is associated with single nucleotide gene polymorphisms in renalase, a newly described secreted flavoprotein with oxidoreductase activity. Gene deletion causes hypertension, and aggravates acute ischemic kidney (AKI) and cardiac injury. Independent of its intrinsic enzymatic activities, extracellular renalase activates MAPK signaling and prevents acute kidney injury (AKI) in wild type (WT) mice. Therefore, we sought to identity the receptor for extracellular renalase.. RP-220 is a previously identified, 20 amino acids long renalase peptide that is devoid of any intrinsic enzymatic activity, but it is equally effective as full-length recombinant renalase at protecting against toxic and ischemic injury. Using biotin transfer studies with RP-220 in the human proximal tubular cell line HK-2 and protein identification by mass spectrometry, we identified PMCA4b as a renalase binding protein. This previously characterized plasma membrane ATPase is involved in cell signaling and cardiac hypertrophy. Co-immunoprecipitation and co-immunolocalization confirmed protein-protein interaction between endogenous renalase and PMCA4b. Down-regulation of endogenous PMCA4b expression by siRNA transfection, or inhibition of its enzymatic activity by the specific peptide inhibitor caloxin1b each abrogated RP-220 dependent MAPK signaling and cytoprotection. In control studies, these maneuvers had no effect on epidermal growth factor mediated signaling, confirming specificity of the interaction between PMCA4b and renalase.. PMCA4b functions as a renalase receptor, and a key mediator of renalase dependent MAPK signaling.

Topics: Acute Kidney Injury; Cell Line; Cytoprotection; Down-Regulation; Epidermal Growth Factor; Essential Hypertension; Humans; Hypertension; Mitogen-Activated Protein Kinases; Monoamine Oxidase; Plasma Membrane Calcium-Transporting ATPases; Polymorphism, Single Nucleotide; Protein Interaction Domains and Motifs; Signal Transduction

The epithelial sodium channel (ENaC) is expressed in the aldosterone-sensitive distal nephron where it performs sodium reabsorption from the lumen. We have recently shown that ENaC activity contributes to the development of salt-induced hypertension as a result of deficiency of EGF level. Previous studies revealed that Rho GDP-dissociation inhibitor α (RhoGDIα) is involved in the control of salt-sensitive hypertension and renal injury via Rac1, which is one of the small GTPases activating ENaC. Here we investigated the intracellular mechanism mediating the involvement of the RhoGDIα/Rac1 axis in the control of ENaC and the effect of EGF on ENaC in this pathway. We demonstrated that RhoGDIα is highly expressed in the cortical collecting ducts of mice and rats, and its expression is down-regulated in Dahl salt-sensitive rats fed a high salt diet. Knockdown of RhoGDIα in cultured cortical collecting duct principal cells increased ENaC subunits expression and ENaC-mediated sodium reabsorption. Furthermore, RhoGDIα deficiency causes enhanced response to EGF treatment. Patch clamp analysis reveals that RhoGDIα significantly decreases ENaC current density and prevents its up-regulation by RhoA and Rac1. Inhibition of Rho kinase with Y27632 had no effects on ENaC response to EGF either in control or RhoGDIα knocked down cells. However, EGF treatment increased levels of active Rac1, which was further enhanced in RhoGDIα-deficient cells. We conclude that changes in the RhoGDIα-dependent pathway have a permissive role in the Rac1-mediated enhancement of ENaC activity observed in salt-induced hypertension.

Topics: Animals; Cells, Cultured; Epidermal Growth Factor; Epithelial Cells; Epithelial Sodium Channels; Gene Expression Regulation; Hypertension; Ion Transport; Kidney Tubules, Collecting; Membrane Potentials; Mice; Mice, Inbred C57BL; Neuropeptides; Patch-Clamp Techniques; rac1 GTP-Binding Protein; Rats; Rats, Inbred Dahl; Renal Reabsorption; rho Guanine Nucleotide Dissociation Inhibitor alpha; RNA, Small Interfering; Signal Transduction; Sodium Chloride, Dietary

Hypertension is an important risk factor for cardiovascular disease and there is increasing evidence that inflammation and abnormal immune responses are involved in the pathogenesis of hypertension. However, the data on the association between specific cytokine concentrations and hypertension are inconsistent. We have evaluated the association between 12 cytokines/growth factors and the presence of different degrees of hypertension, comparing these concentrations to values in a healthy group of subjects. The concentrations of interleukin (IL)-1α, -1β, -2, -4, -6, -8, -10, tumor necrosis factor (TNF-α), interferon-γ (IFN-γ), monocyte chemoattractant protein (MCP-1), epidermal growth factor, and vascular endothelial growth factor were measured in 155 hypertensive patients and 148 healthy subjects, using EV-3513 cytokine biochip arrays, a competitive chemiluminescence immunoassay. Univariate and multivariate analyses were used to evaluate the association of specific cytokines and growth factors with systolic blood pressure (SBP) and diastolic blood pressure (DBP). Hypertensive subjects had higher serum concentrations of IL-1α, -2, -8, vascular endothelial growth factor, IFN-γ, TNF-α, MCP-1, and epidermal growth factor; and lower concentrations of anti-inflammatory cytokine, IL-10 (P < .05), compared with the healthy individuals. The serum concentrations of IL-4, -6, and -1β did not differ between the hypertensive subjects and control group. Univariate and multivariate analyses revealed that IL-1α and IFN-γ were independent predictors of a high SBP, while IFN-γ, IL-1α, TNF-α, and MCP-1 remained statistically significant for DBP after correction for age, gender, Body mass index, smoking, fasting blood glucose, and triglycerides. There was a significant association between the concentrations of several cytokines and hypertension. These associations may either be related to common underlying factors that cause hypertension and may also be proinflammatory or because these inflammatory cytokines might directly be involved in the etiology of hypertension.

Topics: Biomarkers; Blood Pressure; C-Reactive Protein; Cytokines; Epidermal Growth Factor; Female; Humans; Hypertension; Immunoassay; Inflammation; Male; Middle Aged; Prognosis; Vascular Endothelial Growth Factor A

Various stimuli, including hormones and growth factors, modulate epithelial sodium channels (ENaCs), which fine-tune Na(+) absorption in the kidney. Members of the EGF family are important for maintaining transepithelial Na(+) transport, but whether EGF influences ENaC, perhaps mediating salt-sensitive hypertension, is not well understood. Here, the ENaC inhibitor benzamil attenuated the development of hypertension in Dahl salt-sensitive rats. Feeding these salt-sensitive rats a high-salt diet led to lower levels of EGF in the kidney cortex and enhanced the expression and activity of ENaC compared with feeding a low-salt diet. To directly evaluate the role of EGF in the development of hypertension and its effect on ENaC activity, we infused EGF intravenously while continuously monitoring BP of the salt-sensitive rats. Infusion of EGF decreased ENaC activity, prevented the development of hypertension, and attenuated glomerular and renal tubular damage. Taken together, these findings indicate that cortical EGF levels decrease with a high-salt diet in salt-sensitive rats, promoting ENaC-mediated Na(+) reabsorption in the collecting duct and the development of hypertension.

Topics: Amiloride; Animals; Blood Pressure; Disease Models, Animal; Epidermal Growth Factor; Epithelial Sodium Channels; Hypertension; Kidney; Rats; Rats, Inbred Dahl; Sodium Chloride, Dietary

A delay in the diagnosis and treatment of iatrogenic obstructive ureteral injury is the most important prognostic factor for worse results in terms of lesion repair and renal function recovery. The role of the time of relief in determining the onset of renal failure and arterial hypertension in patients with obstructive ureteral injury was evaluated. In addition, we analyzed the prognostic value of the ratio of urinary epidermal growth factor-to-monocyte chemotactic peptide-1 in predicting long-term renal function deterioration.. A total of 76 patients with obstructive ureteral injury and treated with reconstructive procedures were prospectively enrolled in the study. The ratio of epidermal growth factor-to-monocyte chemotactic peptide-1 was evaluated 4 weeks after the relief of obstruction. After a median followup of 60.8 months, estimated creatinine clearance and (99m)technetium-mercaptoacetyltriglycine scan were evaluated.. Within 2 weeks of the obstructive ureteral injury 36 patients underwent surgery for relief of obstruction while in the remaining 40 patients the surgery was performed after more than 2 weeks. Significant differences between the 2 groups were observed regarding mean mercaptoacetyltriglycine clearance of the obstructed kidney (p <0.0001), estimated creatinine clearance (p <0.001) and ratio of epidermal growth factor-to-monocyte chemotactic peptide-1 (p <0.0001). There was a direct correlation between mercaptoacetyltriglycine clearance and epidermal growth factor-to-monocyte chemotactic peptide-1 (rs = 0.78, p <0.0001). Patients with a time of relief greater than 2 weeks had a higher incidence of postoperative hypertension. On logistic regression the time of relief was the only significant variable predicting renal function deterioration (OR 1.49, p = 0.01).. Patients who experience delayed relief of obstructive ureteral injury have decreased long-term renal function as suggested by the lower values of estimated creatinine clearance and mercaptoacetyltriglycine clearance, and are at risk for hypertension or exacerbation of preexisting hypertension.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Biomarkers; Blood Pressure; Chemokine CCL2; Child; Child, Preschool; Creatine; Disease Progression; Epidermal Growth Factor; Female; Follow-Up Studies; Humans; Hypertension; Male; Middle Aged; Plastic Surgery Procedures; Prognosis; Prospective Studies; Renal Insufficiency; Time Factors; Ureter; Ureteral Obstruction; Urologic Surgical Procedures; Young Adult

The epithelial sodium channel (ENaC) participates in the regulation of plasma sodium and volume, and gain of function mutations in the human channel cause salt-sensitive hypertension. Roles for the arachidonic acid epoxygenase metabolites, the epoxyeicosatrienoic acids (EETs), in ENaC activity have been identified; however, their mechanisms of action remain unknown. In polarized M1 cells, 14,15-EET inhibited amiloride-sensitive apical to basolateral sodium transport as effectively as epidermal growth factor (EGF). The EET effects were associated with increased threonine phosphorylation of the ENaC β and γ subunits and abolished by inhibitors of (a) mitogen-activated protein kinase/extracellular signal-regulated kinase kinase/extracellular signal regulated kinases 1 and 2 (MEK/ERK1/2) and (b) EGF receptor signaling. CYP2C44 epoxygenase knockdown blunted the sodium transport effects of EGF, and its 14,15-EET metabolite rescued the knockdown phenotype. The relevance of these findings is indicated by (a) the hypertension that results in mice administered cetuximab, an inhibitor of EGF receptor binding, and (b) immunological data showing an association between the pressure effects of cetuximab and reductions in ENaCγ phosphorylation. These studies (a) identify an ERK1/2-dependent mechanism for ENaC inhibition by 14,15-EET, (b) point to ENaC as a proximal target for EET-activated ERK1/2 mitogenic kinases, (c) characterize a mechanistic commonality between EGF and epoxygenase metabolites as ENaC inhibitors, and (d) suggest a CYP2C epoxygenase-mediated pathway for the regulation of distal sodium transport.

Topics: 8,11,14-Eicosatrienoic Acid; Animals; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antihypertensive Agents; Cetuximab; Cytochrome P-450 Enzyme System; Cytochrome P450 Family 2; Epidermal Growth Factor; Epithelial Sodium Channels; Extracellular Signal-Regulated MAP Kinases; Gene Expression Regulation; Humans; Hypertension; Kidney; Male; Mice; Models, Biological; Phosphorylation

Activation of the epidermal growth factor receptors (EGFR) plays an important role in the regulation of the kidney blood circulation and ion transport. The mRNA content of the epidermal growth factor (Egf) and its receptor (Egfr) genes were studied in the cortical and medullar parts of the kidney of rats with stress sensitive arterial hypertension (ISIAH strain) and normotensive WAG rats. There were no differences in the Egf expression between the rat strains at rest and under emotional stress in both the cortical and medullary kidney zones. As for Egfr transcription, it was significantly higher in the cortical and medullary parts of the ISIAH kidneys at rest as compared to the control WAG. Emotional stress induced no significant changes in the Egfr transcription in the cortical kidney parts of both rat strains. But prominent enhancement of Egfr transcription after emotional stress was observed in the kidney medulla of the WAG rats: it became the same as in the ISIAH rats at rest. It was suggested that the stress hormones might be involved in the regulation of Egfr transcription, and this connection between stress and Egfr gene activity might play a significant role in the kidney involvement in pathogenesis of stress sensitive arterial hypertension.

Topics: Adrenal Cortex; Adrenal Medulla; Animals; Blood Pressure; Epidermal Growth Factor; ErbB Receptors; Gene Expression Regulation; Hypertension; Kidney; Male; Rats; RNA, Messenger; Stress, Psychological

Increased medial arterial thickness is a structural change in pulmonary arterial hypertension (PAH). The role of smooth muscle hypertrophy in this process has not been well studied. Bone morphogenetic proteins (BMPs), transforming growth factor (TGF)-beta1, serotonin (or 5-hydroxytryptamine; 5-HT), and endothelin (ET)-1 have been implicated in PAH pathogenesis. We examined the effect of these mediators on human pulmonary artery smooth muscle cell size, contractile protein expression, and contractile function, as well on the roles of glycogen synthase kinase (GSK)-3beta and p70 ribosomal S6 kinase (p70S6K), two proteins involved in translational control, in this process. Unlike epidermal growth factor, BMP-4, TGF-beta1, 5-HT, and ET-1 each increased smooth muscle cell size, contractile protein expression, fractional cell shortening, and GSK-3beta phosphorylation. GSK-3beta inhibition by lithium or SB-216763 increased cell size, protein synthesis, and contractile protein expression. Expression of a non-phosphorylatable GSK-3beta mutant blocked BMP-4-, TGF-beta1-, 5-HT-, and ET-1-induced cell size enlargement, suggesting that GSK-3beta phosphorylation is required and sufficient for cellular hypertrophy. However, BMP-4, TGF-beta1, 5-HT, and ET-1 stimulation was accompanied by an increase in serum response factor transcriptional activation but not eIF2 phosphorylation, suggesting that GSK-3beta-mediated hypertrophy occurs via transcriptional, not translational, control. Finally, BMP-4, TGF-beta1, 5-HT, and ET-1 treatment induced phosphorylation of p70S6K and ribosomal protein S6, and siRNAs against p70S6K and S6 blocked the hypertrophic response. We conclude that mediators implicated in the pathogenesis of PAH induce pulmonary arterial smooth muscle hypertrophy. Identification of the signaling pathways regulating vascular smooth muscle hypertrophy may define new therapeutic targets for PAH.

Topics: Actins; Bone Morphogenetic Protein 4; Endothelin-1; Epidermal Growth Factor; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Humans; Hypertension; Hypertrophy; Indoles; Lithium Chloride; Maleimides; Muscle Contraction; Potassium Chloride; Pulmonary Artery; Ribosomal Protein S6 Kinases, 70-kDa; RNA, Messenger; Serotonin; Signal Transduction; Transforming Growth Factor beta1

Hypertension is a mechanism-based toxic effect of drugs that inhibit the vascular endothelial growth factor signaling pathway (VSP). Substantial evidence exists for managing hypertension as a chronic condition, but there are few prospectively collected data on managing acute hypertension caused by VSP inhibitors. The Investigational Drug Steering Committee of the National Cancer Institute convened an interdisciplinary cardiovascular toxicities expert panel to evaluate this problem, to make recommendations to the Cancer Therapy Evaluation Program on further study, and to structure an approach for safe management by treating physicians. The panel reviewed: the published literature on blood pressure (BP), hypertension, and specific VSP inhibitors; abstracts from major meetings; shared experience with the development of VSP inhibitors; and established principles of hypertension care. The panel generated a consensus report including the recommendations on clinical concerns summarized here. To support the greatest possible number of patients to receive VSP inhibitors safely and effectively, the panel had four recommendations: 1) conduct and document a formal risk assessment for potential cardiovascular complications, 2) recognize that preexisting hypertension will be common in cancer patients and should be identified and addressed before initiation of VSP inhibitor therapy, 3) actively monitor BP throughout treatment with more frequent assessments during the first cycle of treatment, and 4) manage BP with a goal of less than 140/90 mmHg for most patients (and to lower, prespecified goals in patients with specific preexisting cardiovascular risk factors). Proper agent selection, dosing, and scheduling of follow-up should enable maintaining VSP inhibition while avoiding the complications associated with excessive or prolonged elevation in BP.

Topics: Adult; Aged; Antihypertensive Agents; Antineoplastic Agents; Blood Pressure; Blood Pressure Determination; Blood Pressure Monitoring, Ambulatory; Epidermal Growth Factor; Female; Humans; Hypertension; Male; Middle Aged; Population Surveillance; Risk Factors; Signal Transduction

We showed previously that vascular smooth muscle cells (VMSC) from spontaneously hypertensive rats (SHR) exhibit increased proliferation. The present study was undertaken to examine whether the enhanced levels of endogenous angiotensin (ANG) II and endothelin (ET)-1 contribute to the enhanced proliferation of VSMC from SHR and to further investigate the underlying mechanisms responsible for this response. The enhanced proliferation of VSMC from SHR compared with Wistar-Kyoto (WKY) rats was attenuated by losartan, BQ-123, BQ-788, and AG-1478, inhibitors of AT(1), ET(A), ET(B) and epidermal growth factor (EGF-R) receptors, respectively. In addition, BQ-123 and BQ-788 also attenuated the enhanced production of superoxide anion (O(2)(-)) and NADPH oxidase activity. Furthermore, diphenyleneiodonium (DPI, inhibitor of NADPH oxidase), N-acetyl-L-cysteine (NAC, O(2)(-) scavenger), and PP2 (inhibitor of c-Src) also inhibited the augmented proliferation of VSMC from SHR to WKY levels. In addition, the enhanced phosphorylation of EGF-R in VSMC from SHR compared with WKY was also attenuated by inhibitors of AT(1), ET(A), ET(B), and EGF-R but not by inhibitors of platelet-derived growth factor receptor or insulin-like growth factor receptor. Furthermore, the enhanced phosphorylation of ERK1/2 in VSMC from SHR was also attenuated by AT(1), ET(A), ET(B), c-Src, and EGF-R inhibitors. The phosphorylation of c-Src was significantly augmented in VSMC from SHR compared with VSMC from WKY and was attenuated by DPI and NAC. These data suggest that endogenous vasoactive peptides, through increased oxidative stress and resultant activation of c-Src, transactivate EGF-R, which through mitogen-activated protein (MAP) kinase signaling may contribute to the hyperproliferation of VSMC from SHR.

Topics: Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Animals; Cell Proliferation; Cells, Cultured; CSK Tyrosine-Protein Kinase; Disease Models, Animal; Endothelin A Receptor Antagonists; Endothelin B Receptor Antagonists; Endothelin-1; Enzyme Inhibitors; Epidermal Growth Factor; ErbB Receptors; Free Radical Scavengers; Hyperplasia; Hypertension; Mitogen-Activated Protein Kinases; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; NADPH Oxidases; Oxidative Stress; Phosphorylation; Protein-Tyrosine Kinases; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Receptor, Angiotensin, Type 1; Receptor, Endothelin A; Receptor, Endothelin B; Signal Transduction; src-Family Kinases; Superoxides

1. Studies have documented the proliferative effects of epidermal growth factor (EGF) on neural progenitor cells in the normal or injured brain. The effect of EGF on post-stroke cerebral expression of nestin, a marker of neural progenitor cells, has not been examined in hypertensive rats. 2. In the present study, adult renovascular hypertensive Sprague-Dawley rats underwent either real or sham middle cerebral artery occlusion (MCAO). Intracerebroventricular injections of either 1 microg EGF or vehicle (0.01 mol/L phosphate-buffered saline containing 0.1 mg/mL rat serum albumin) were made 24 and 48 h after MCAO. Then, 1, 2, 3 and 4 weeks after MCAO, the postural reflex was evaluated in a blinded fashion before rat brains were processed to determine the infarct volume plus immunoreactivity for nestin and/or glial fibrillary acidic protein (GFAP). Another group of rats was used to quantify nestin expression using western blot analysis. 3. Middle cerebral artery occlusion resulted in a focal infarct that was largest at 1 week and diminished gradually over the time. The impaired postural reflex followed a similar time-course. In addition, MCAO induced a marked increase in nestin expression in both hemispheres, with a higher expression in the right hemisphere; this change was maximal at 1 week and largely subsided at 3 or 4 weeks. Within the right hemisphere, nestin expression was most pronounced in the subventricular and peri-infarct zones. Most nestin-immunoreactive cells were also positive for GFAP. 4. Thus, EGF treatment significantly increases nestin expression, reduces infarct volume and ameliorates postural reflex impairment in adult hypertensive rats.

Topics: Animals; Blood Pressure; Cerebral Infarction; Drug Evaluation, Preclinical; Epidermal Growth Factor; Hypertension; Injections, Intraventricular; Intermediate Filament Proteins; Male; Mental Disorders; Nerve Tissue Proteins; Nestin; Posture; Rats; Rats, Sprague-Dawley; Reflex

This study identified, on the integrative level, two components of the ANG II signaling pathway that lay downstream from the ANG II type 1 (AT(1)) receptor and are critically involved in maintaining vascular relaxation in cerebral resistance arteries. In these experiments, the relaxation of isolated middle cerebral arteries (MCA) in response to ACh (10(-9)-10(-5) M), iloprost (10(-16)-10(-11) g/ml), and reduced PO(2) was lost and the ratio of phospho-ERK/ERK1/2 was significantly reduced in aortas of male Sprague-Dawley rats fed a high-salt (HS; 4% NaCl) diet to suppress plasma ANG II levels. In salt-fed rats, relaxation of MCA in response to these vasodilator stimuli was restored by chronic (3 days) intravenous infusion of either ANG II (5 ngxkg(-1)xmin(-1)) or epidermal growth factor (EGF; 2 microg/h). The protective effect of ANG II infusion to restore vascular relaxation was eliminated by coinfusion of either the EGF receptor kinase inhibitor AG-1478 (20 microg/h), the ERK1/2 inhibitor PD-98059 (10 microg/h), or the protein synthesis inhibitor cycloheximide (5 microg/h). In rats fed a low-salt (0.4% NaCl) diet, MCA relaxation in response to ACh, reduced PO(2), and iloprost was eliminated by intravenous infusion of AG-1478, PD-98059, or cycloheximide. In ANG II-infused rats fed HS diet, and in rats fed LS diet, vasodilator responses to reduced PO(2) and iloprost were unaffected by the p38 MAP kinase inhibitor SB-203580 and the phosphatidylinositol 3-kinase inhibitor wortmannin. These findings indicate that maintenance of normal vascular relaxation mechanisms by ANG II in rat MCA requires activation of the EGF receptor kinase and ERK1/2.

Topics: Angiotensin II; Animals; Blood Pressure; Disease Models, Animal; Dose-Response Relationship, Drug; Epidermal Growth Factor; ErbB Receptors; Hypertension; Infusions, Intravenous; Male; Middle Cerebral Artery; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Phosphorylation; Protein Kinase Inhibitors; Protein Synthesis Inhibitors; Rats; Rats, Sprague-Dawley; Receptor Cross-Talk; Receptor, Angiotensin, Type 1; Signal Transduction; Sodium Chloride, Dietary; Vasodilation; Vasodilator Agents

The epithelial sodium channel (ENaC) is expressed in a variety of tissues, including the renal collecting duct, where it constitutes the rate-limiting step for sodium reabsorption. Liddle's syndrome is caused by gain-of-function mutations in the beta and gamma subunits of ENaC, resulting in enhanced Na reabsorption and hypertension. Epidermal growth factor (EGF) causes acute inhibition of Na absorption in collecting duct principal cells via an extracellular signal-regulated kinase (ERK)-dependent mechanism. In experiments with primary cultures of collecting duct cells derived from a mouse model of Liddle's disease (beta-ENaC truncation), it was found that EGF inhibited short-circuit current (Isc) by 24 +/- 5% in wild-type cells but only by 6 +/- 3% in homozygous mutant cells. In order to elucidate the role of specific regions of the beta-ENaC C terminus, Madin-Darby canine kidney (MDCK) cell lines that express beta-ENaC with mutation of the PY motif (P616L), the ERK phosphorylation site (T613A), and C terminus truncation (R564stop) were created using the Phoenix retroviral system. All three mutants exhibited significant attenuation of the EGF-induced inhibition of sodium current. In MDCK cells with wild-type beta-ENaC, EGF-induced inhibition of Isc (<30 min) was fully reversed by exposure to an ERK kinase inhibitor and occurred with no change in ENaC surface expression, indicative of an effect on channel open probability (P(o)). At later times (>30 min), EGF-induced inhibition of Isc was not reversed by an ERK kinase inhibitor and was accompanied by a decrease in ENaC surface expression. Our results are consistent with an ERK-mediated decrease in ENaC open probability and enhanced retrieval of sodium channels from the apical membrane.

Topics: Amiloride; Amino Acid Motifs; Animals; Butadienes; Cell Line; Disease Models, Animal; Dogs; Down-Regulation; Epidermal Growth Factor; Epithelial Sodium Channel Blockers; Epithelial Sodium Channels; Hypertension; Kidney; Membrane Potentials; Mice; Mice, Transgenic; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Mutation; Nitriles; Phosphorylation; Protein Kinase Inhibitors; Protein Structure, Tertiary; Protein Transport; Sodium; Sodium Channel Blockers; Syndrome; Transfection

We investigated whether increased contractile responsiveness to epidermal growth factor (EGF) is associated with altered activation of mitogen-activated protein kinase (MAPK) in the aortic smooth muscle of deoxycorticosterone acetate (DOCA)-salt hypertensive rats. EGF induced contraction and MAPK activity in aortic smooth muscle strips, which were significantly increased in tissues from the DOCA-salt hypertensive rats compared with those from sham-operated rats. AG1478, PD98059, and LY294002, inhibitors of EGF receptor (EGFR) tyrosine kinase, MAPK/extracellular signal-regulated kinase (ERK) kinase, and phosphatidylinositol 3-kinase (PI3K), respectively, inhibited the contraction and the activity of ERK1/2 that were elevated by EGF. Y27632 and GF109203X, inhibitors of Rho kinase and protein kinase C, respectively, attenuated EGF-induced contraction, with no diminution of ERK1/2 activity. Although EGF also elevated the activity of EGFR tyrosine kinase in both sham-operated and DOCA-salt hypertensive rats, the expression and the magnitude of activation did not differ between strips. These results strongly suggest that EGF induces contraction by the activation of ERK1/2, which is regulated by the PI3K pathway in the aortic smooth muscle of DOCA-salt hypertensive rats.

Topics: Animals; Aorta; Desoxycorticosterone; Dose-Response Relationship, Drug; Epidermal Growth Factor; ErbB Receptors; Hypertension; Male; Mitogen-Activated Protein Kinases; Muscle, Smooth, Vascular; Phosphatidylinositol 3-Kinases; Rats; Rats, Sprague-Dawley; Sodium Chloride, Dietary; Vasoconstriction

Ossification disturbance in femoral head reportedly is seen in the Spontaneously Hypertensive rats (SHR) between ages of 10 and 20 weeks. We investigated serum and tissue levels of insulin-like growth factor-1 (IGF-1) and vascular endothelial growth factor (VEGF) in SHR relevant to the ossification disturbance and osteonecrosis of the femoral head. Serum levels of IGF-1 and VEGF were significantly lower in SHR than in Wistar Kyoto rats (WKY) at weeks 5, 10, 15 and 20 (p<0.005). The incidence of histological ossification disturbance of the femoral head was higher in SHR (59%) than in WKY (40%) at week 20. Lower serum and local levels of VEGF in SHR appeared to be related to the incomplete ossification of the femoral heads. Immunohistochemical study showed significantly lower numbers of IGF-1 and VEGF positive chondrocytes in the femoral epiphyseal cartilage of SHR than in those of WKY at weeks 10, 15 and 20. Our results suggest that local and/or systemic levels of IGF-1 and VEGF between ages of 5 and 20 weeks might play roles in the pathogenesis of ossifi cation disturbance of the femoral head in SHR.

Topics: Animals; Chondrocytes; Epidermal Growth Factor; Femur Head Necrosis; Growth Plate; Hypertension; Immunohistochemistry; Insulin-Like Growth Factor I; Ossification, Heterotopic; Rats; Rats, Inbred SHR; Rats, Inbred WKY

Matrix metalloproteinase (MMP)-dependent shedding of heparin-binding epidermal growth factor (HB-EGF) and subsequent activation of the EGF receptor (EGFR) in the cardiovasculature is emerging as a unique mechanism signaling growth effects of diverse G protein-coupled receptors (GPCRs). Among these GPCRs are adrenoceptors and angiotensin receptors that contribute to the pathogenesis of hypertension through their vasoconstrictive and growth effects. Focusing on alpha(1b)-adrenoceptors, we suggest here that MMP-dependent activation of the EGFR promotes vasoconstriction as well as growth. We identified MMP-7 as a major HB-EGF sheddase in rat mesenteric arteries and alpha(1b)-adrenoceptors, angiotensin receptors, and hypertension-stimulated MMP-7 activity. Adrenoceptors stimulated EGFR autophosphorylation in arteries, and this transactivation was opposed by the MMP-7 inhibitor GM6001 as well as MMP-7-specific antibodies. In isolated microperfused arteries, blockade of EGFR transactivation with inhibitors of the EGFR (AG1478 and PD153035), HB-EGF (CRM197 and neutralizing antibodies), or MMPs (doxycycline) inhibited adrenergic vasoconstriction. In spontaneously hypertensive rats but not in normotensive rats, the inhibition of MMPs with doxycycline (19.2 mg/d from week 7 until week 12) reduced systolic blood pressure and attenuated HB-EGF shedding in the mesenteric arteries. These findings suggest a previously unknown mechanism of vasoregulation whereby agonists of certain GPCRs (such as adrenoceptors and angiotensin receptors) activate MMPs (such as MMP-7) that shed EGFR ligands (such as HB-EGF), which then activate the EGFR, thereby promoting vasoconstriction as well as growth. Because this mechanism is triggered by agonists typically overexpressed in hypertension, its blockade may have therapeutic potential for simultaneously inhibiting pathological vasoconstriction and growth in hypertensive disorders.

Topics: Adrenergic alpha-1 Receptor Agonists; Adrenergic alpha-Agonists; Animals; Arteries; Blood Pressure; Enzyme Activation; Epidermal Growth Factor; ErbB Receptors; Heparin-binding EGF-like Growth Factor; Hypertension; Intercellular Signaling Peptides and Proteins; Male; Matrix Metalloproteinase 7; Phenylephrine; Rats; Rats, Inbred WKY; Rats, Sprague-Dawley; Signal Transduction; Vasoconstriction

G-protein-coupled receptor (GPCR) agonists are well-known inducers of cardiac hypertrophy. We found that the shedding of heparin-binding epidermal growth factor (HB-EGF) resulting from metalloproteinase activation and subsequent transactivation of the epidermal growth factor receptor occurred when cardiomyocytes were stimulated by GPCR agonists, leading to cardiac hypertrophy. A new inhibitor of HB-EGF shedding, KB-R7785, blocked this signaling. We cloned a disintegrin and metalloprotease 12 (ADAM12) as a specific enzyme to shed HB-EGF in the heart and found that dominant-negative expression of ADAM12 abrogated this signaling. KB-R7785 bound directly to ADAM12, suggesting that inhibition of ADAM12 blocked the shedding of HB-EGF. In mice with cardiac hypertrophy, KB-R7785 inhibited the shedding of HB-EGF and attenuated hypertrophic changes. These data suggest that shedding of HB-EGF by ADAM12 plays an important role in cardiac hypertrophy, and that inhibition of HB-EGF shedding could be a potent therapeutic strategy for cardiac hypertrophy.

Topics: ADAM Proteins; ADAM12 Protein; Angiotensin II; Animals; Aorta, Thoracic; Cardiomegaly; Disease Models, Animal; Disintegrins; Epidermal Growth Factor; ErbB Receptors; Glycine; GTP-Binding Proteins; Heart Ventricles; Heparin-binding EGF-like Growth Factor; Hydroxamic Acids; Hypertension; Intercellular Signaling Peptides and Proteins; Male; Membrane Proteins; Metalloendopeptidases; Phenylephrine; Protease Inhibitors; Protein Processing, Post-Translational; Rats; Signal Transduction; Systole; Transcriptional Activation

With a view to evaluating the putative involvement of cytokine gene variants in human essential hypertension, we carried out an association (case-control) study on 174 unrelated nationals (81 hypertensives and 93 normotensives) from the Abu Dhabi Emirate (UAE), a genetically homogeneous population also characterised by the absence of traditional confounding factors such as alcohol consumption and smoking. To that end, we targeted our investigation to five candidate gene loci-transforming growth factor beta1 (TGF-beta1), interferon gamma (IFN-gamma), epidermal growth factor (EGF), interleukin-1 beta (IL-1beta) and tumour-necrosis factor (TNF-alpha) genes. We investigated the distribution of genotypes and alleles of the six following dimorphic variants: TGF-beta1(*)10(T>C) and TGF-beta1(*)25(G>C), located at codons 10 and 25, respectively, of TGF-beta1; T874A in intron 1 of IFN-gamma; G61A in exon 1 of EGF; TaqI dimorphism at +3962 (exon 5) of IL-1beta; and -308A>G in the promoter of TNF-alpha. These six bi-allelic markers were visualised by methods based on the techniques of amplification refractory mutation system-polymerase chain reaction (for TGF-beta1, IFN-gamma, EGF and TNF-alpha) and by polymerase chain reaction-TaqI restriction endonuclease analysis in the case of IL-1beta. In each of the two groups (normotensives and hypertensives), genotype frequencies of all six markers occurred in Hardy-Weinberg proportions. There were, however, no statistical differences in the allele and genotype frequencies of any of the six markers between the two groups of subjects: TGF-beta1(*)10C frequencies were 0.46 and 0.49 (chi(2)=0.61; 2 d.f.; P=0.74) and TGF-beta1(*)25C were 0.07 and 0.08 (chi(2)=0.61; 2 d.f.; P=0.74) amongst normotensives and hypertensives, respectively; p(IFN-gamma(*)A874) were 0.41 in normotensives versus 0.46 in hypertensives (chi(2)=3.07; 2 d.f.; P=0.22); p(EGF (*)G61) were 0.51 versus 0.58 (chi(2)=1.76; 2 d.f.; P=0.41); p[IL-1beta (*)TaqI(+)] were 0.43 versus 0.36 (chi(2)=2.08; 2 d.f.; P=0.35); and p(TNF-alpha(*)-308G) were 0.80 versus 0.85 (chi(2)=1.29; 2 d.f.; P=0.53). There was also no difference in distribution and frequencies of haplotypes constructed with combinations of TGF-beta1(*)10(T>C) and TGF-beta1(*)25(G>C) sites. However, although they do not reach statistical significance (which may be due to the relatively restricted number of subjects included in this study), the distribution differences (in normotensives and hypertensives) ob

Topics: Case-Control Studies; Cytokines; Epidermal Growth Factor; Female; Gene Frequency; Genes; Genotype; Humans; Hypertension; Interferon-gamma; Interleukin-1; Male; Middle Aged; Pilot Projects; Retrospective Studies; Transforming Growth Factor beta; Transforming Growth Factor beta1; Tumor Necrosis Factor-alpha; United Arab Emirates

The present studies test the hypothesis that contraction to EGF is dependent on mineralocorticoids and/or an elevation in systolic blood pressure (SBP). Endothelium-denuded thoracic aortas from sham normotensive, N(omega)-nitro-L-arginine (L-NNA) hypertensive, Wistar-Kyoto (WKY), and spontaneously hypertensive rats (SHR) were used in isolated tissue-bath experiments. Maximal contraction to epidermal growth factor [EGF; percentage of phenylephrine (PE; 10 umol/l)-induced contraction] was greater in strips from L-NNA (32 +/- 5%) and SHR (53 +/- 8%) rats compared with sham and WKY rats (17 +/- 1 and 12 +/- 4%, respectively). Wistar-Furth rats became only mildly hypertensive when given DOCA salt (134 +/- 6 mmHg) compared with Wistar rats (176 +/- 9 mmHg), but aortas from both strains had a similarly enhanced contraction to EGF (approximately 9 times the maximal contraction of sham aorta). Furthermore, in vitro incubation of aortas from Wistar and Wistar-Furth rats with aldosterone (10 nmol/l) increased EGF-receptor mRNA expression by >50%. These data indicate that arterial contraction to EGF may occur independent of hypertension and be stimulated by mineralocorticoids.

Topics: Aldosterone; Animals; Aorta, Thoracic; Blood Pressure; Desoxycorticosterone; Dose-Response Relationship, Drug; Enzyme Inhibitors; Epidermal Growth Factor; ErbB Receptors; Hypertension; In Vitro Techniques; Mineralocorticoids; Rats; Rats, Inbred SHR; Rats, Inbred WF; Rats, Sprague-Dawley; Rats, Wistar; RNA, Messenger; Sodium Chloride; Species Specificity; Up-Regulation; Vasoconstriction

We have tested the hypothesis that growth factor signaling pathways are augmented in hypertension, a disease associated with vascular smooth muscle cell growth. Thoracic aorta was dissected from deoxycorticosterone acetate-salt (DOCA-salt) and one kidney, one clip (1K, 1C) hypertensive rats and from sham normotensive rats for use in isolated tissue bath experiments. Systolic blood pressure was significantly higher in DOCA-salt and 1K, 1C than in normotensive sham rats: 192 +/- 7, 185 +/- 10, and 117 +/- 4 mmHg, respectively. Although virtually no contraction to epidermal growth factor (EGF) was observed in endothelium-denuded sham rat aorta [1 +/- 1% phenylephrine (PE) (10 micromol/l)-induced contraction], the maximal EGF-induced contraction was 45 +/- 7% in endothelium-denuded aorta from DOCA-salt hypertensive rats and 39 +/- 7% in aorta from 1K, 1C rats. Although slightly attenuated, a contraction to EGF was still observed in endothelium-intact aortic strips from 28-day DOCA-salt hypertensive rats. We also conducted concentration-response curves to EGF on days 1, 3, 5, 7, 14, and 21 of DOCA-salt therapy. A significant contraction to EGF in aorta from DOCA-salt rats was observed on day 14, when DOCA-salt rats had significantly higher blood pressure than sham rats: 188 +/- 6 and 122 +/- 3 mmHg, respectively. Transforming growth factor-alpha, an agonist of the EGF receptor, contracted DOCA-salt rat aorta (30 +/- 7% PE-induced contraction) but not sham aorta (3 +/- 3%). The EGF receptor tyrosine kinase inhibitor 4,5-dianilinophthalimide (10 micromol/l), the mitogen-activated protein kinase kinase inhibitor PD-098059 (10 micromol/l), and the L-type voltage-gated calcium channel inhibitor diltiazem (1 mol/l), but not the cyclooxygenase inhibitor indomethacin (10 micromol/l), virtually abolished EGF-induced contraction (85, 98, and 99% reduction, respectively). These data support a striking difference in EGF signaling between normotensive and hypertensive animals. Furthermore, they provide evidence that growth factors should be considered vasoconstrictors as well as growth modulators in hypertension.

Topics: Animals; Aorta; Desoxycorticosterone; Epidermal Growth Factor; Hypertension; Hypertension, Renovascular; Male; Rats; Rats, Sprague-Dawley; Reference Values; Sodium Chloride; Vasoconstriction; Vasoconstrictor Agents

Transforming growth factor-beta1 (TGF-beta1) stimulates vascular smooth muscle cell growth in spontaneously hypertensive rats (SHR), but inhibits cell growth in normotensive Wistar- Kyoto (WKY) rats. The present study was undertaken to test the hypothesis that TGF-beta1 might differentially modulate the activities of mitogen-activated protein (MAP) kinase family members (ERK, JNK and p38) in vascular smooth muscle cells of SHR and WKY rats.. MAP kinase activity was measured from cultured vascular smooth muscle cells in response to TGF-1 by specific substrate phosphorylation of myelin basic protein, GST-c-Jun and GST-ATF2.. Exposure of cultured vascular smooth muscle cells from SHR or WKY rats to TGF-beta1 resulted in a marked increase in the activity of ERK, but not of JNK or p38. The increase of ERK activity stimulated by TGF-beta1 appeared similar in time course and extent in both WKY and SHR cells, with increased activity peaking at 15 min of incubation. Epidermal growth factor (EGF) also stimulated the activity of ERK, in both WKY and SHR cells, but nor of JNK or p38, with stimulation of ERK activity by EGF occurring more rapidly in SHR cells than in those from WKY rats. Co-incubation of SHR cells with TGF-beta1 and EGF showed additive effect on ERK activity.. The results provide the first evidence that TGF-beta1 activates ERK in vascular smooth muscle cells of both normotensive and hypertensive rats. The matching response of ERK activation to TGF-1 in SHR cells suggests that the MAP kinase-signaling pathway remains largely unchanged in the regulation of vascular smooth muscle growth by TGF-1 in spontaneously hypertensive rats.

Topics: Animals; Calcium-Calmodulin-Dependent Protein Kinases; Cells, Cultured; Epidermal Growth Factor; Glycogen Synthase Kinase 3; Growth Substances; Hypertension; JNK Mitogen-Activated Protein Kinases; Male; Mitogen-Activated Protein Kinases; Muscle, Smooth, Vascular; p38 Mitogen-Activated Protein Kinases; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Reference Values; Transforming Growth Factor beta

Previous studies have suggested that differences in vascular smooth muscle cell (VSMC) proliferative responses between spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats can be attributed to transforming growth factor-beta (TGF-beta) actions. Because vascular collagen content is reported to be lower in SHR than in WKY rats, in this study we investigated in cell culture whether the differences in collagen content might also be attributed to differential actions of TGF-beta on VSMCs from the two strains. Exposure of VSMCs from WKY to the TGF-beta isoforms -beta1, -beta2, or -beta3 induced rapid, transient elevations in mRNAs encoding collagens alpha1(I), alpha2(I), and alpha1(III); maximum increases were apparent by 2 hours and ranged from twofold [collagen alpha1(III)] to ninefold [collagen alpha1(I)]. Thereafter they returned to near basal levels. When VSMCs from SHR were exposed to these TGF-beta isoforms, only reductions in collagen mRNA levels were observed, persisting for 24 hours. Basic fibroblast growth factor and epidermal growth factor, factors known to stimulate production of the TGF-beta1 isoform in VSMCs, also induced a pattern of gene responses similar to those induced by the TGF-beta isoforms in VSMCs from SHR and WKY rats. The simultaneous presence of TGF-beta did not affect the time course or magnitude of the changes in collagens alpha1(I), alpha2(I), or alpha1(III) mRNA levels in SHR or WKY VSMCs. Examination of the induction of c-myc mRNA and immunoreactive oncoprotein content indicated that c-myc is a likely contributor to the downregulation of the collagen gene activity in both SHR and WKY VSMCs despite the differential regulation of its mRNA by TGF-beta1 in the two VSMC lines. Together these data suggest that in VSMCs from SHR, a number of gene responses to TGF-beta, in addition to cell proliferation, appear to be abnormal compared with WKY rats, and the lower than normal collagen levels observed in the vasculature of SHR may be in part due to abnormalities in TGF-beta responsiveness.

Topics: Animals; Cell Nucleus; Collagen; Epidermal Growth Factor; Fibroblast Growth Factor 2; Hypertension; Male; Muscle, Smooth, Vascular; Proto-Oncogene Proteins c-myc; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Receptor Protein-Tyrosine Kinases; RNA, Messenger; Transforming Growth Factor beta

Dahl salt sensitive rats (DS) developed severe hypertension on four weeks of high salt feeding while the Dahl salt resistant rats (DR) remained normotensive under the same conditions. The specific maximal binding of epidermal growth factor (EGF) in the freshly prepared kidney membranes of high salt fed DS rats was higher than those from DR rats (5.3 +/- 1.9 vs. 1.6 +/- 0.62 fmoles/mg protein, p<0.001). Scatchard analysis of EGF binding in the kidney showed one class of receptors in the DR (K(d) = 0.75 +/- 0.05 nM) as well as in the DS rats (K(d)=0.69 +/- 0.06 nM). The EGF binding in the aortic membranes of DS rats was also high compared to DR rats (24.98 +/- 5.52 vs. 13.20 +/- 4.10 fmoles/mg protein, p < 0.001). Scatchard analysis of EGF binding in the aorta showed one class of receptors in the DR aorta with a K(d) of 0.70 +/- 0.06 nM. On the other hand, in the DS rat aorta two classes of receptors, a high affinity form (K(d)=0.05 +/- 0.01 nM) and a low affinity form (K(d)=3.5 +/- 0.3 nM) were noted. The induction of a high affinity species of EGF receptors in the aorta, appears to be a mechanism unique to the salt fed DS rats.

Topics: Animals; Aorta; Blood Pressure; Epidermal Growth Factor; ErbB Receptors; Gene Expression; Hypertension; Kidney; Kinetics; Male; Myocardium; Protein Binding; Protein Processing, Post-Translational; Rats; Rats, Inbred Dahl; RNA, Messenger; Sodium Chloride, Dietary

1. We examined the proliferative rates of cultured astrocytes isolated from stroke-prone spontaneously hypertensive rats (SHRSP) and stroke-resistant spontaneously hypertensive rats (SHRSR). Wistar-Kyoto rats (WKY) were used as a control for SHRSP and SHRSR. 2. In the presence of 10% fetal bovine serum (FBS), the doubling time for astrocytes from SHRSP and SHRSR was significantly shorter than WKY. 3. When quiescent astrocytes derived from SHRSP or SHRSR were released from serum-deprivation, the DNA synthesis was stimulated 13.3-fold and 12.5-fold, respectively, whereas only a 7.76-fold increase was observed in WKY astrocytes. 4. Further we studied the effects of two growth factors, epidermal growth factor (EGF) and fibroblast growth factor (FGF) on astrocytes proliferation. EGF induced greater DNA synthesis in SHRSP and SHRSR astrocytes compared with WKY astrocytes, although FGF had little or no effect. 5. Total cholesterol levels in SHRSP astrocytes and SHRSR astrocytes were significantly lower than that of WKY astrocytes, which was consistent with our previous observations in cultured vascular smooth muscle cells. 6. There was no difference in morphology among the cultured astrocytes from the three strains. 7. The abnormality of growth rate and cell membranes composition of astrocytes might be closely related to the genetic phenotypes (acute death of neurons and oedema of astrocytes) of SHRSP or SHRSR.

Topics: Animals; Astrocytes; Cattle; Cell Cycle; Cell Division; Cell Membrane; Cells, Cultured; Cerebrovascular Disorders; Cholesterol; DNA; Epidermal Growth Factor; Fibroblast Growth Factors; Hypertension; Immunohistochemistry; Microscopy, Electron; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Serum Albumin; Thymidine

Epidermal growth factor receptor concentrations (EGFR) in placentae and fetal membranes from 25 normal and 25 hypertension-complicated pregnancies were analysed by a radioreceptor technique. Higher EGFR concentrations were found in placentae from hypertension-complicated pregnancies than in those from normal pregnancies (median 125.0 fmol/mg protein, range: 33.4-190.7 versus median 50.3 fmol/mg protein, range 21.4-184.0) (P = 0.0002). EGFR concentrations were significantly lower in fetal membranes than in placental tissue, both in normal membranes (median 31.7, range 4.8-92.0 versus median 50.3, range 21.4-184.0) (P = 0.0004) and in hypertension-complicated pregnancies (median 65.0, range 16.8-125.0 versus median 125.0, range 33.4-190.7) (P = 0.0001). A statistically significant inverse correlation between EGFR concentrations and gestational age was found in placentae (r = 0.53, P = 0.0061) and fetal membranes (r = 0.56, P = 0.0032) from hypertension-complicated pregnancies. Multiple regression analyses demonstrated that hypertensive disease is more closely associated with EGFR concentrations than gestational age and fetal weight in placental tissue and fetal membranes. Our findings suggest that hypertensive disorders in pregnancy are associated with elevated EGFR concentrations in both the placenta and fetal membranes.

Topics: Epidermal Growth Factor; ErbB Receptors; Extraembryonic Membranes; Female; Humans; Hypertension; Placenta; Pregnancy; Pregnancy Complications, Cardiovascular; Radioligand Assay; Reference Values; Regression Analysis

The mechanisms of vascular structural alterations in hypertension were studied in cultured adventitial fibroblasts isolated from aortas of spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats. Basic fibroblast growth factor (bFGF)-, epidermal growth factor (EGF)-, or platelet-derived growth factor (PDGF)-induced DNA synthesis and phospholipase C activity were estimated by determining 3H-thymidine incorporation and 3H-inositol phosphate production, respectively. The role of protein tyrosine kinases was assessed by stimulating the cells in the presence of tyrphostin, a protein tyrosine kinase inhibitor. Both the mitogenic potency of bFGF, EGF, and PDGF and the phospholipase C activity elicited by these factors were increased markedly in SHR (v WKY) fibroblasts. SHR fibroblasts were significantly less sensitive to tyrphostin inhibition of bFGF-induced 3H-thymidine incorporation than WKY fibroblasts, whereas when the cells were stimulated with EGF, PDGF, or 5% serum, SHR and WKY fibroblasts were equally sensitive to tyrphostin inhibition. At doses that abolished bFGF-induced 3H-thymidine incorporation, tyrphostin did not affect bFGF-induced 3H-inositol phosphate production. These results indicate that in aortic fibroblasts phospholipase C activation is not sufficient for bFGF-induced DNA synthesis. They suggest that tyrosine kinase activation is a necessary step in the transduction of bFGF mitogenic signal and plays an important role in the enhanced DNA synthesis exhibited by SHR (v WKY) cells. Therefore, one may envisage that bFGF contributes, through paracrine/autocrine mechanisms, to the vascular smooth muscle hyperplasia/hypertrophy in SHR.

Topics: Animals; Aorta; Arteries; Catechols; DNA; Epidermal Growth Factor; Fibroblast Growth Factor 2; Fibroblasts; Hypertension; Male; Nitriles; Platelet-Derived Growth Factor; Protein-Tyrosine Kinases; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Signal Transduction; Thymidine; Type C Phospholipases; Tyrphostins

The present study examines the role of serum growth factors in the proliferative response and Na-K-Cl cotransport activity of vascular smooth muscle cells from Milan normotensive (MNS) and hypertensive (MHS) rats. Cells from thoracic aorta of both strains were cultured in 10% serum medium and made quiescent by 72 hours in 0.3% serum medium. MHS cells grown with 10% serum had a shorter population doubling time than MNS cells between passages 8 and 12 (13.8 +/- 1.7 versus 20.1 +/- 1.6 hours, P < .01, n = 4). MHS cells also exhibited a higher response of thymidine incorporation into nucleic acid to serum, epidermal, and platelet-derived growth factor BB. In MHS cells epidermal (100 ng/mL) and platelet (50 ng/mL) growth factors increased thymidine incorporation 2- and 10-fold, respectively. In MNS cells epidermal factor did not induce a significant response, and that of platelet factor was twofold lower than in MHS cells. Binding curves revealed a higher number of receptors for platelet than epidermal growth factor in both strains and a similar number of both receptors in MHS and MNS cells. Quantitative immunoblots of these receptor proteins confirmed the observation that the greater proliferation of MHS cells could not be related to a higher number of growth factor receptors. Cotransport activity (bumetanide-sensitive 86Rb influx in nanomoles per milligram protein per 5 minutes) was found to be significantly higher in MHS cells (16 +/- 3, n = 18) than MNS cells (8 +/- 3, n = 15) at confluence as well as in the log phase of serum-stimulated growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Becaplermin; Binding Sites; Carrier Proteins; Cell Division; Epidermal Growth Factor; Hypertension; Kinetics; Muscle, Smooth, Vascular; Platelet-Derived Growth Factor; Proto-Oncogene Proteins c-sis; Rats; Rats, Mutant Strains; Reference Values; Sodium-Potassium-Chloride Symporters; Sodium-Potassium-Exchanging ATPase

Hypertension is frequently associated with insulin resistance. We evaluated the effects of pioglitazone, an agent that increases insulin sensitivity, on the development of hypertension in the Dahl salt-sensitive (Dahl-S) rat and in the one-kidney, one-clip Sprague-Dawley rat. We also evaluated the effects of pioglitazone on growth of cultured preglomerular renal arteriolar smooth muscle cells. In Dahl-S rats fed a 3% NaCl diet, tail systolic blood pressures and direct arterial pressures were lower (P < 0.05) in pioglitazone-treated (20 mg/kg daily by gavage for 3 wk) than in control rats (n = 10 rats/group). In one-kidney, one-clip Sprague-Dawley rats, systolic blood pressures were also lower in pioglitazone-treated animals (P < 0.0001). In vitro, proliferation of arteriolar smooth muscle cells was stimulated (P < 0.01) by insulin, epidermal growth factor (EGF), and fetal calf serum (FCS); pioglitazone (5 microM) reversibly inhibited (P < 0.01) insulin-, EGF-, and FCS-induced proliferation. Pioglitazone (0.01-100 microM) also inhibited insulin- (1 mU/ml), EGF- (100 ng/ml), and 5% FCS-induced [3H]thymidine incorporation in a concentration-dependent manner (P < 0.01). Thus pioglitazone attenuated the development of hypertension in the Dahl-S rat and the one-kidney, one-clip rat. The ability of pioglitazone to inhibit growth of vascular smooth muscle may contribute to its hypotensive effect.

Topics: Animals; Arterioles; Blood Pressure; Cell Division; Epidermal Growth Factor; Hypertension; Hypoglycemic Agents; Insulin; Kidney; Male; Muscle, Smooth; Pioglitazone; Rats; Rats, Mutant Strains; Rats, Sprague-Dawley; Sodium Chloride; Thiazoles; Thiazolidinediones; Thymidine

Topics: Animals; Aorta; DNA; Epidermal Growth Factor; Hypertension; Muscle, Smooth, Vascular; Protein-Tyrosine Kinases; Rats; Rats, Inbred SHR; Rats, Inbred WKY

Epidermal growth factor (EGF) may have a modulatory role in renal growth and function. The aim of the present study was to evaluate whether urinary excretion of EGF is altered in psoriatic patients with or without arterial hypertension. The glomerular filtration rate was similar in psoriatics as compared with age- and sex-matched controls, whereas urinary EGF (microgram/g creatinine) was significantly reduced in psoriatics: normotensive subjects, 29.52 +/- 3.51 (psoriatics) versus 44.31 +/- 1.20 (controls, p less than 0.05); hypertensive subjects, 19.67 +/- 3.96 (psoriatics) versus 30.11 +/- 1.52 (controls, p less than 0.05). The urinary EGF excretion was lower in males than in females, save for hypertensive psoriatics. Urinary EGF correlated inversely with age and directly with urinary kallikrein excretion. Urinary kallikrein activity was reduced and microalbuminuria increased in hypertensive psoriatics. These alterations might suggest that initial deterioration of renal function is present in psoriasis.

Topics: Epidermal Growth Factor; Female; Glomerular Filtration Rate; Humans; Hypertension; Kallikreins; Kidney; Male; Middle Aged; Psoriasis; Sex Factors

Topics: Animals; Cell Division; Cells, Cultured; DNA; Epidermal Growth Factor; Hypertension; Muscle, Smooth, Vascular; Proto-Oncogene Proteins c-fos; Rats; Rats, Inbred SHR; RNA, Messenger; Transforming Growth Factor beta

Although enhanced growth of the vascular myocyte is believed to play a role in hypertensive cardiovascular disease, the cellular basis of altered growth regulation is not completely understood. The present study demonstrates that in the presence of 10% fetal calf serum, the logarithmic growth rate of cultured mesenteric artery myocytes of the spontaneously hypertensive rat (SHR) is similar to that of the normotensive Wistar-Kyoto (WKY) control rat. However, in the presence of low levels of fetal calf serum, SHR myocytes respond to epidermal growth factor (EGF) with increased growth, whereas WKY cells do not. This difference does not result from different numbers or affinities of EGF receptors in these cell lines. Examination of EGF-induced growth responses of SHR and WKY myocytes in the presence of varying levels of insulin or fetal calf serum indicates that, compared with WKY myocytes, SHR myocytes have a lower requirement for factors that confer competence to respond to EGF. Another property of the SHR myocytes is an elevation of free intracellular Ca2+. To determine whether a difference in cellular Ca2+ metabolism might play a role in the differential growth response, growth of myocytes in medium containing 0.25, 0.75, or 1.25 mM extracellular Ca2+ and 5% fetal calf serum was examined. Myocytes of SHR showed enhanced growth in the presence of 5% fetal calf serum at all levels of extracellular Ca2+. It is concluded that, although vascular myocytes of SHR and WKY rats have the capacity to grow at similar rates, under limiting conditions, the SHR myocyte growth response is enhanced.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Cells, Cultured; Culture Media; Epidermal Growth Factor; Hypertension; Muscle Development; Muscle, Smooth, Vascular; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Time Factors

When cultured in the presence of fetal calf serum, arterial smooth muscle cells from spontaneously hypertensive rats (SHR) proliferate more rapidly and are more numerous at confluency than cells from normotensive Wistar-Kyoto (WKY) animals. The phenomenon has been demonstrated in several laboratories but its molecular origin remains unclear. On the other hand phospholipase C activation and c-fos transcription are early events able to trigger cell mitosis. Therefore, the enhancement of inositol phosphates formation induced in SHR cells by various vasoactive agents and growth factors suggests that this enzyme might be implicated in the abnormal proliferation triggered by serum. In this case a unique molecular abnormality would be responsible for both arterial hypercontractility and dystrophy encountered in hypertension. In order to test this hypothesis we have compared DNA replication, phospholipase C activation, and c-jun and c-fos nuclear protooncogene transcriptions stimulated by fetal calf serum (FCS), vasoactive agents (angiotensin II and vasopressin), and epithelial growth factor (EGF) in SHR and WKY rat cells. The results obtained with these various agonists tested under the same experimental conditions confirm that the classical pathogenic diagram: (PLC hyperactivation----increase in c-fos transcription----enhanced cell proliferation) may apply to the action of vasoactive agents which are only slightly mitogenic on SHR cells, but not to the very important effect of fetal calf serum. Indeed, FCS stimulated inositol phosphate formation and c-jun and c-fos transcription, but none of these parameters was enhanced in SHR cells. Phospholipase C activation may exert some control upon DNA replication, as its partial inhibition by pertussis toxin coincided with an equivalent decrease in thymidine incorporation. It is, however, not absolutely required for the onset of DNA replication in aortic smooth muscle cells, as shown by the results obtained with EGF under the same experimental conditions. An abnormal molecular reaction different from PLC activation is therefore responsible for the enhanced proliferation of cultured SHR aortic smooth muscle cells, and several cell alterations may concur to the formation of the hypertensive arteriopathy.

Topics: Angiotensin II; Animals; Aorta; Cell Division; Cells, Cultured; DNA; DNA Replication; Enzyme Activation; Epidermal Growth Factor; Gene Expression; Hypertension; Muscle, Smooth, Vascular; Oncogenes; Proto-Oncogene Proteins c-fos; Proto-Oncogene Proteins c-jun; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Thymidine; Transcription, Genetic; Type C Phospholipases; Vasopressins

Vascular smooth muscle cells from spontaneously hypertensive rats (SHR) exhibited enhanced growth rates in culture when compared to cells from their normotensive, Wistar-Kyoto (WKY) counterparts. Proliferation rates were dependent on supplementation levels of fetal calf serum (FCS) in culture medium and the passage number of the cells studied. Cells from hypertensive animals were more responsive to a number of agonists, as assessed by activation of S6 kinase and elevation of intracellular pH than those derived from WKY animals. Furthermore, SHR-derived cells exhibited enhanced turnover of phosphoinositides when exposed to epidermal growth factor or angiotensin II as compared to cells from normotensive rats treated in the same way. The latter cells were, however, more susceptible to growth inhibition by heparin than their hypertensive counterparts and possessed twice the number of specific cell surface heparin receptors as SHR-derived cells. Both cell types showed a marked stimulation of proliferation rates when they were cultured on extracellular matrix coated plasticware. Matrices elaborated by SHR-derived cells were more stimulatory to growth than those derived from WKY sources.

Topics: Animals; Aorta, Thoracic; Carotid Arteries; Culture Techniques; Epidermal Growth Factor; Growth Substances; Heparin; Hypertension; Male; Muscle Development; Muscle, Smooth, Vascular; Rats; Rats, Inbred SHR; Rats, Inbred WKY

Aortic smooth muscle cells from spontaneously hypertensive rats (SHR) exhibit inappropriate proliferation characteristics in culture that suggest a modified response to serum mitogens or growth factors. The present study compares vascular smooth muscle cells from SHR and normotensive Wistar-Kyoto (WKY) rats with respect to their proliferative and functional response to growth factors. Specific attention was focused on the interaction of these vascular smooth muscle cells with epidermal growth factor. An increased growth rate of vascular smooth muscle cells from SHR (vs. WKY rats) was observed when cells were cultured in the presence of serum (10% and 0.5%), but not under serum-free conditions. The additional presence of low serum concentrations (0.5%) was required for epidermal growth factor to elicit a proliferative response, whereupon smooth muscle cells from SHR displayed an increased (vs. WKY rats) growth rate. Saturation binding of [125I]epidermal growth factor to intact smooth muscle cells indicated a twofold increase in receptor density in SHR-derived cells (p less than 0.001 vs. WKY rats) without an alteration in affinity for the growth factor. Cells derived from SHR also exhibited greater functional responsiveness to epidermal growth factor when compared with smooth muscle cells from WKY rats as evidenced by amplifications of both S6 kinase activation, phosphoinositide catabolism, elevation of intracellular pH, and DNA synthesis (nuclear labeling). We conclude that increased responsiveness of SHR-derived smooth muscle cells to epidermal growth factor could contribute to alterations in vascular smooth muscle growth and tone that may be fundamental to the pathogenesis of hypertension and atherosclerosis.

Topics: Animals; Cell Division; Cells, Cultured; DNA; Dose-Response Relationship, Drug; Epidermal Growth Factor; Hydrogen-Ion Concentration; Hypertension; Male; Muscle, Smooth, Vascular; Phosphatidylinositols; Protein Kinases; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Ribosomal Protein S6 Kinases

Aortic vascular smooth muscle cells isolated from spontaneously hypertensive rats (SHR) grow nearly twice as fast in vitro as cells isolated from several normotensive control strains of rats. We have previously shown that DNA synthesis in SHR cells from both young and adult animals in response to epidermal growth factor is selectively enhanced compared with normotensive controls, suggesting that epidermal growth factor may be at least partly responsible for the enhanced growth rate. To determine whether the enhanced DNA synthesis in response to epidermal growth factor in SHR cells is mediated via an enhanced epidermal growth factor receptor tyrosine kinase, we measured thymidine incorporation in epidermal growth factor-stimulated vascular smooth muscle cells in the presence of the highly specific tyrosine kinase inhibitor genistein. The 50% inhibitory dose (IC50) of genistein was higher for the SHR vascular smooth muscle cells than for the normotensive Wistar rat (NBR; National Institutes of Health Black rat). This suggests that the increased DNA synthesis in response to epidermal growth factor in SHR cells is a result of higher receptor tyrosine kinase activity initiating further intracellular signals.

Topics: Animals; Cells, Cultured; DNA; Epidermal Growth Factor; Flavonoids; Genistein; Hypertension; Isoflavones; Muscle, Smooth, Vascular; Protein-Tyrosine Kinases; Rats; Rats, Inbred SHR; Rats, Inbred Strains

To understand the intrinsic mechanisms of vascular smooth muscle cell proliferation, we studied the growth of cultured rat aortic smooth muscle from spontaneously hypertensive rats (SHR) and their normotensive controls, Wistar-Kyoto rats (WKY), under basal conditions and after stimulation. Cell growth was assessed by the determination of cell number, and incorporation of 3H-thymidine into newly-synthesized DNA. We demonstrated that vascular smooth muscle cells from SHR proliferate faster and grow to a greater density, regardless of the initial plating number. The growth difference was not due to different plating efficiencies. Significantly higher 3H-thymidine incorporation was observed in vascular smooth muscle cells from SHR when the cells were stimulated by calf serum, platelet-derived growth factor or epidermal growth factor. Exposure to calf serum elicited an excessive expression of c-myc and c-fos in the first hour after stimulation. These results provide evidence of the hyper-responsiveness of vascular smooth muscle cells from SHR aortae to growth stimuli.

Topics: Animals; Cell Division; DNA; Epidermal Growth Factor; Hypertension; Muscle, Smooth, Vascular; Platelet-Derived Growth Factor; Rats; Rats, Inbred SHR