lithium-chloride and Hypertension

The triterpene oleanolic acid (OA) is known to possess antihypertensive actions. In the present study we to compared the effects of the triterpene on mean arterial blood pressure (MAP) and kidney function following acute administration in normotensive animals with those of its related oleanane synthetic derivatives (brominated oleanolic acid, Br-OA and oleanolic acid methyl ester, Me-OA). We also used experimental models of hypertension to further explore the effects of sub-chronic oral OA treatment and evaluated influences on oxidative status.. OA was extracted from dried flower buds of Syzygium aromaticum using a previously validated protocol in our laboratory. Me-OA and Br-OA were synthesized according to a method described. Rats were supplemented with lithium chloride (12 mmol L-1) prior to experimentation in order to raise plasma lithium to allow measurements of lithium clearance and fractional excretion (FELi) as indices of proximal tubular Na+ handling. Anaesthetized animals were continuously infused via the right jugular with 0.077M NaCl. MAP was measured via a cannula inserted in the carotid artery, and urine was collected through a cannula inserted in the bladder. After a 3.5 h equilibration, MAP, urine flow, electrolyte excretion rates were determined for 4 h of 1 h control, 1.5 h treatment and 1.5 h recovery periods. OA, Me-OA and Br-OA were added to the infusate during the treatment period. We evaluated sub-chronic effects on MAP and kidney function in normotensive Wistar rats and in two animal models of hypertension, spontaneously hypertensive rats (SHR) and Dahl salt-sensitive (DSS) rats, during 9-week administration of OA (p.o.). Tissue oxidative status was examined in these animals at the end of the study. Increasing evidence suggests that and renal function disturbances and oxidative stress play major roles in the pathogenesis of hypertension.. Acute infusion OA and oleanane derivatives displayed qualitatively similar effects in decreasing MAP and increasing urinary Na+ outputs. The drugs increased the FENa and FELi without influencing GFR indicating that at least part of the overall natriuretic effect involved proximal tubular Na+ reabsorption. Sub-chronic OA administration (p.o.) also elicited hypotensive responses in Wistar, DSS and SHR rats. The MAP lowering effect was more marked in hypertensive animals and were positively correlated with increased urinary Na+ excretion. Compared with respective control rats, OA treatment reduced malondialdehyde (MDA, a marker of lipid peroxidation) and increased activities of antioxidant enzymes; superoxide dismutase and glutathione peroxidase in hepatic, cardiac and renal tissues.. OA and oleanane derivatives have similar effects on MAP, kidney function and oxidative stress. The amelioration of oxidative stress and blood pressure lowering effects by OA are more marked in hypertensive animals and correlated with an increased urinary Na+ output.. The results of this study are novel in that they show 1) a correlation between blood pressure reduction and increased urinary Na+ excretion by OA, 2) a more marked MAP reduction in hypertensive animals and 3) a drug-induced decrease in proximal tubule Na+ reabsorption. The results may also be clinically relevant because OA is effective via oral administration.

Topics: Aldosterone; Animals; Antihypertensive Agents; Antioxidants; Arginine Vasopressin; Blood Pressure; Glutathione Peroxidase; Hypertension; Kidney Tubules, Proximal; Lithium Chloride; Male; Malondialdehyde; Oleanolic Acid; Rats; Rats, Inbred Dahl; Rats, Inbred SHR; Rats, Wistar; Reactive Oxygen Species; Sodium; Sodium Chloride; Superoxide Dismutase; Syzygium

The aim of this study was to examine the effects of GSK-3 β inhibitors compared with PRE and POS in spontaneously hypertensive rats (SHR). Isolated hearts were submitted to the following protocols: IC: 45 min global ischemia (GI) and 1-hour reperfusion (R); PRE: a cycle of 5 min GI and 10 minutes of R prior to 45 min GI; POS: three cycles of 30 sec GI/30 sec R at the start of R. Other hearts received lithium chloride (LiCl) or indirubin-3'-monoxime,5-iodo-(IMI) as GSK-3 β inhibitors. All interventions reduced the infarct size observed in IC group. The expressions of P-GSK-3 β and P-Akt decreased in IC and were restored after PRE, POS, and GSK-3 β inhibitors treatments. An increase of cytosolic MnSOD activity and lipid peroxidation and a decrease of GSH content observed in IC hearts were attenuated in PRE, POS, and LiCl or IMI treatments. An increase of P-GSK-3 β /VDAC physical association and a partial recovery of mitochondrial permeability were also detected after interventions. These data show that, in SHR hearts, GSK-3 β inhibitors mimic the cardioprotection afforded by PRE and POS and suggest that a decrease in mitochondrial permeability mediated by P-GSK-3 β /VDAC interaction is a crucial event.

Topics: Animals; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Heart; Humans; Hypertension; Indoles; Ischemic Postconditioning; Ischemic Preconditioning; Lipid Peroxidation; Lithium Chloride; Organ Culture Techniques; Oximes; Phosphorylation; Proto-Oncogene Proteins c-akt; Rats; Reperfusion Injury

Topics: Antihypertensive Agents; Antimanic Agents; Benzimidazoles; Benzoates; Drug Interactions; Female; Humans; Hypertension; Lithium Chloride; Middle Aged; Psychotic Disorders; Telmisartan

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

Myocardial hypertrophy has been recognized to be an adaptive response to a variety of external stimuli (e.g., myocardial infarction, pressure overload, catecholamine treatment, endocrine disorders) that are involved in several subcellular factors that mediate signaling pathways, from external stimuli to nuclear protein synthesis. Glycogen synthase kinase-3beta (GSK-3beta) is one of the subcellular factors that regulate nuclear transcription factors, such as activated T-cell (NFAT) proteins, that are related to gene programming during cardiac hypertrophy. On the other hand, GSK-3beta, known as a regulator of cardiomyocyte growth in Wnt signaling of cardiogenesis, is involved in beta-catenin degradation. Inhibition of GSK-3beta has been reported to induce cardiac hypertrophy. Tateishi et al. demonstrated in an aortic constriction-induced acute hypertrophy model using 6-week-old Wister rats that if GSK-3b is inhibited by LiCl up-regulated beta-catenin expression and additional hypertrophy were observed. They suggested that Li(2+) had an additive effect on pressure overload-induced hypertrophy through the GSK-3beta-beta-catenin pathway. Their article provides promising information on the mechanism of hypertrophic myocyte growth during acute pressure overload.

Topics: Animals; Aorta, Abdominal; Atrial Natriuretic Factor; beta Catenin; Blood Pressure; Cardiovascular Agents; Disease Models, Animal; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Hypertension; Hypertrophy, Left Ventricular; Ligation; Lithium Chloride; Phosphorylation; Protein Kinase Inhibitors; Rats; RNA, Messenger; Serine; Time Factors

A large number of diverse signaling molecules in cell and animal models participate in the stimulus-response pathway through which the hypertrophic growth of the myocardium is controlled. However, the mechanisms of signaling pathway including the influence of lithium, which is known as an inhibitor of glycogen synthase kinase-3beta, in pressure overload hypertrophy remain unclear. The aim of our study was to determine whether glycogen synthase kinase-3beta inhibition by lithium has acute effects on the myocyte growth mechanism in a pressure overload rat model.. First, we created a rat model of acute pressure overload cardiac hypertrophy by abdominal aortic banding. Protein expression time courses for beta-catenin, glycogen synthase kinase-3beta, and phosphoserine9-glycogen synthase kinase-3beta were then examined. The rats were divided into four groups: normal rats with or without lithium administration and pressure-overloaded rats with or without lithium administration. Two days after surgery, Western blot analysis of beta-catenin, echo-cardiographic evaluation, left ventricular (LV) weight, and LV atrial natriuretic peptide mRNA levels were evaluated.. We observed an increase in the level of glycogen synthase kinase-3beta phosphorylation on Ser 9. A significant enhancement of LV heart weight (P < 0.05) and interventricular septum and posterior wall thickness (P < 0.05) with pressure-overloaded hypertrophy in animals treated with lithium were also observed. Atrial natriuretic peptide mRNA levels were significantly increased with pressure overload hypertrophy in animals treated with lithium.. We have shown in an animal model that inhibition of glycogen synthase kinase-3beta by lithium has an additive effect on pressure overload cardiac hypertrophy.

Topics: Animals; Aorta, Abdominal; Atrial Natriuretic Factor; beta Catenin; Blood Pressure; Blotting, Western; Cardiovascular Agents; Disease Models, Animal; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Hypertension; Hypertrophy, Left Ventricular; Ligation; Lithium Chloride; Male; Phosphorylation; Polymerase Chain Reaction; Protein Kinase Inhibitors; Rats; Rats, Wistar; RNA, Messenger; Serine; Time Factors; Ultrasonography

The mitochondrial permeability transition (MPT) pore may serve as the end-effector of cardioprotective mechanisms, namely the mitochondrial K(ATP) channels and glycogen synthase kinase-3beta (GSK-3beta). We recently showed that augmented MPT pore induction contributes to pressure overload-induced exacerbation of infarct size. This study tests the hypotheses that (i) elevation in perfusion pressure attenuates cardioprotection associated with activation of mitochondrial KATP channels or inhibition of GSK-3beta and (ii) perfusion pressure modulates the regulation of the MPT pore by mitochondrial KATP channels and/or GSK-3beta.. Langendorff-perfused hearts were subjected to a regional ischemia-reperfusion insult at a perfusion pressure of either 80 or 160 cm H2O. The perfusion medium contained no drug, diazoxide (80 micromol/l; mitochondrial KATP channel opener), lithium chloride (LiCl, 1 mmol/l; nonselective inhibitor of GSK-3beta), SB-216763 (3 micromol/l; selective inhibitor of GSK-3beta), cyclosporine A (0.2 micromol/l; inhibitor of MPT pore induction), glibenclamide (50 micromol/l; inhibitor of KATP channels), and the combination of cyclosporine A and glibenclamide or the combination of glibenclamide and LiCl.. The increase in perfusion pressure in the absence of a drug caused larger infarcts, an effect associated with poorer recovery of function following ischemia reperfusion. Treatment with either diazoxide or cyclosporine A reduced infarct size at both perfusion pressures but in contrast to diazoxide, cyclosporine A was more protective at the higher pressure. On the other hand, LiCl and SB-216763 reduced infarct size at both pressures, with the effect more marked at the higher perfusion pressure. Glibenclamide did not affect infarct size but eliminated the cardioprotective effect of cyclosporine A while having no effect on LiCl-induced cardioprotection.. Perfusion pressure primarily affects GSK-3beta-mediated regulation of MPT pore formation in the ischemic reperfused heart.

Topics: Animals; Cardiotonic Agents; Cyclosporine; Diazoxide; Disease Models, Animal; Glyburide; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Hypertension; In Vitro Techniques; Indoles; Lithium Chloride; Male; Maleimides; Mitochondria, Heart; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Perfusion; Potassium Channel Blockers; Potassium Channels; Protein Kinase Inhibitors; Rats; Rats, Sprague-Dawley; Ventricular Function, Left; Ventricular Pressure

A number of potential interactions between angiotensin-converting enzyme inhibitors and lithium have been described in the literature. In the present study, we investigated the effects of a low-dose combination treatment with lithium and captopril on survival and stroke prevention in salt-loaded, stroke-prone spontaneously hypertensive rats (SHRSP).. Eight-week-old saline-drinking SHRSP (n = 21 per group) were treated with vehicle, LiCl (1 mmol/kg per day), captopril (25 mg/kg per day) and captopril plus LiCl for up to 37 weeks. Body weight, salt water intake blood pressure and mortality were recorded throughout the experimental period. Plasma renin activity, plasma lithium concentration and urinary excretion of albumin, sodium and potassium were measured at different time points.. Captopril treatment doubled the life expectancy when compared with vehicle-treated rats. Lithium alone had minor effects on survival but led to a dramatic increase in survival when added to captopril (mean survival time > 237 versus 147 days, P < 0.001). Systolic blood pressure increased with age in all treatment groups but was comparable in the captopril-treated and the captopril-plus-lithium-treated groups. Plasma renin activity as well as urinary sodium and potassium excretion did not differ between both groups. In the captopril group a striking fivefold increase of albuminuria occurred between 14 and 26 weeks of age, while this progression was completely abolished by the addition of lithium.. Our results demonstrate that the addition of lithium to captopril dramatically prolong the effects of the angiotensin-converting enzyme inhibitor on survival in salt-loaded SHRSP. This effect was independent of a reduction in blood pressure.

Topics: Albuminuria; Angiotensin-Converting Enzyme Inhibitors; Animals; Antihypertensive Agents; Blood Pressure; Captopril; Hypertension; Lithium; Lithium Chloride; Male; Potassium; Rats; Rats, Inbred SHR; Renin; Sodium; Sodium, Dietary; Stroke

The effects of daily, intraperitoneal injections of LiCl (3 mEq/kg) on systolic blood pressure (SBP) and adrenal catecholamine levels were measured in spontaneously hypertensive rats (SHR) and in normotensive Wistar-Kyoto rats (WKY). Control animals from each strain were injected with equivalent volumes (0.1 ml/100 g b.wt.) of 0.9% saline (0.15 mEq/kg). SBP in LiCl-treated SHR was significantly lower (p less than 0.05) than that of saline-treated SHR (177 +/- 7 vs. 196 +/- 4 mm Hg, respectively) after one week. After two weeks SBP was lower in LiCl SHR than in saline controls, but this difference was not significant. While SBP of both LiCl and saline treated WKY was not significantly different (146 +/- 4 vs. 147 +/- 8 mm Hg, respectively), SBP in both WKY groups remained lower than the SBP for either group of SHR. LiCl induced a significant weight loss in the SHR, but not in the WKY. Adrenal norepinephrine and epinephrine were significantly (p less than 0.05) higher in LiCl-treated rats of both strains; dopamine was also higher in LiCl-treated rats of both strains, but significant only between SHR-LiCl and SHR controls. It appears that LiCl's effect in slowing the development of hypertension is independent of its action on adrenal catecholamines. The SHR's increased sensitivity to LiCl, relative to weight loss and SBP, may reflect differences in genetic or physiological status of the animal compared to WKY. These differences may be associated with alterations in membrane ion transport systems.

Topics: Adrenal Medulla; Animals; Blood Pressure; Chlorides; Epinephrine; Hypertension; Lithium; Lithium Chloride; Male; Norepinephrine; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Sympathetic Nervous System

The role of vasopressin as a pressor agent to the hypertensive process was examined. Vasopressin plays a major role in the pathogenesis of DOCA-salt hypertension, since the elevation of blood pressure was not substantial in the rats with lithium-treated diabetes insipidus after DOCA-salt treatment. Administration of DDAVP which has antidiuretic action but minimal vasopressor effect failed to increase blood pressure to the levels observed after administration of AVP. Furthermore, the pressor action of vasopressin appears to be important in the development of this model of hypertension, since the enhanced pressor responsiveness to the hormone was observed in the initial stage of hypertension. Increased secretion of vasopressin from neurohypophysis also promotes the function of the hormone as a pathogenetic factor in hypertension. An unproportional release of vasopressin compared to plasma osmolality may be induced by the absence of an adjusting control of angiotensin II forming and receptor binding capacity for sodium balance in the brain. However, the role of vasopressin remains to be determined in human essential hypertension.

Topics: Animals; Blood Pressure; Chlorides; Deamino Arginine Vasopressin; Desoxycorticosterone; Hypertension; Injections, Intravenous; Lithium; Lithium Chloride; Male; Rats; Receptors, Angiotensin; Salts; Vasopressins

Topics: Blood Pressure; Blood Pressure Determination; Diet, Sodium-Restricted; Heart Failure; Humans; Hypertension; Lithium; Lithium Chloride; Sodium; Sodium Chloride, Dietary; Sodium, Dietary