atrial-natriuretic-factor and Pheochromocytoma

Adenosine induces expression of the tyrosine hydroxylase (TH) gene in PC12 cells. However, it is suggested that atrial natriuretic peptide (ANP) inhibits expression of this gene. Using real-time PCR and luciferase reporter assays we found that ANP significantly decreases the adenosine-induced transcription of the TH gene. Results of measurements of cyclic nucleotide concentrations indicated that ANP-induced accumulation of cGMP inhibits the adenosine-induced increase in cAMP level. Using selective phosphodiesterase 2 (PDE2) inhibitors and a synthetic cGMP analog activating PDE2, we found that PDE2 is involved in coupling the ANP-triggered signal to the cAMP metabolism. We have established that ANP-induced elevated levels of cGMP as well as cGMP analog stimulate hydrolytic activity of PDE2, leading to inhibition of adenosine-induced transcription of the TH gene. We conclude that ANP mediates negative regulation of TH gene expression via stimulation of PDE2-dependent cAMP breakdown in PC12 cells.

Topics: Adenosine; Adrenal Gland Neoplasms; Animals; Atrial Natriuretic Factor; Cyclic AMP; Cyclic AMP Response Element-Binding Protein; Cyclic GMP; Cyclic Nucleotide Phosphodiesterases, Type 2; Gene Expression Regulation, Neoplastic; Models, Biological; PC12 Cells; Pheochromocytoma; Promoter Regions, Genetic; Rats; RNA, Messenger; Transcription, Genetic; Tyrosine 3-Monooxygenase

Since 1992, adrenalectomy for pheochromocytoma has been recognized as a safe and efficient technique when performed by a laparoscopic approach. Most of the cases of pheochromocytomas treated as such and published in the literature were not associated with malignant hypertension and acute heart failure. We report the case of a 23-year-old woman who presented with this clinical picture and show that laparoscopic adrenalectomy may be as safe and efficient as conventional adrenalectomy when performed in this situation. The intraoperative changes in the secretion of catecholamines, endothelin-1, angiotensin II, N- and C-terminus of atrial natriuretic factor prohormone were also analyzed. Noradrenaline release during tumor dissection was associated with a stimulation of atrial natriuretic factor.

Topics: Adrenal Gland Neoplasms; Adrenalectomy; Adult; Angiotensin II; Atrial Natriuretic Factor; Blood Pressure; Endothelin-1; Epinephrine; Female; Heart Failure; Humans; Laparoscopy; Monitoring, Intraoperative; Norepinephrine; Pheochromocytoma; Protein Precursors

The aim of this study was to evaluate plasma levels of ANF in patients with catecholamine-secreting tumors with and without hypertension and to relate ANF secretion to levels of plasma and urinary catecholamines and blood pressure. Twenty-one pheochromocytoma (15 with sustained, 6 with paroxysmal hypertension), 6 neuroblastoma (1 hypertensive) patients and 28 aged-matched controls were studied in basal conditions. Plasma and urinary norepinephrine (NE),epinephrine (E), dopamine (DA) and DOPA were determined by HPLC-ED and plasma ANF by RIA. Both neuroblastoma and pheochromocytoma patients had significantly higher plasma ANF levels than controls. Neuroblastomas showed higher ANF concentration than pheochromocytomas. No differences were found in plasma ANF between hypertensive and normotensive patients. Pheochromocytomas with ANF levels within the normal range had plasma and urinary NE and urinary DA and DOPA levels significantly higher than patients with high ANF. Plasma ANF levels were unrelated to systolic or diastolic blood pressure or heart rate. A negative correlation between plasma ANF and urinary DA was found only in the patients groups. In conclusion, plasma ANF was increased in pheochromocytoma and neuroblastoma patients. Our data suggest that the excessive catecholamine secretion is not responsible for the increased ANF secretion in these patients. The significance of the relationships among plasma ANF and urinary and plasma catecholamines requires further investigation.

Topics: Abdominal Neoplasms; Adolescent; Adrenal Gland Neoplasms; Adult; Aged; Atrial Natriuretic Factor; Biomarkers, Tumor; Blood Pressure; Catecholamines; Child; Child, Preschool; Female; Humans; Hypertension; Male; Middle Aged; Multiple Endocrine Neoplasia; Neoplasm Staging; Neuroblastoma; Pheochromocytoma; Urinary Bladder Neoplasms

The effect of the natriuretic peptides ANP, BNP and CNP on cGMP formation and immediate early gene expression was investigated in PC12 phaeochromocytoma and C6 glioma cell lines. The three natriuretic peptides were shown to rapidly induce c-fos, TIS8/egr-1 and junB mRNA expression in both cell lines, via stimulation of the cGMP pathway. CNP stimulated cGMP formation and gene induction more potently than the other peptides in C6 cells, and this was statistically significant. In contrast, the three peptides produced similar gene induction in PC12 cells, despite the higher cGMP accumulation evoked by ANP or BNP. CNP was also found to increase DNA binding activity of the transcription factor AP1 in both cell types, demonstrating that natriuretic peptides potentially regulate key cellular gene expression.

Topics: Animals; Atrial Natriuretic Factor; Genes, Immediate-Early; Glioma; PC12 Cells; Pheochromocytoma; Rats; Tumor Cells, Cultured

Pheochromocytoma is a unique type of hypertension caused by excessive production of catecholamines by the chromaffin tumor. Pheochromocytoma, a potentially life-threatening disease, is a rare cause of hypertension. The incidence varies from 0.1 to 0.8% of hypertensive population. The author's experience is based on 138 patients treated in one institution from 1956 to 1995. Hormonal activity of pheochromocytoma varies considerably, influencing the pattern, of blood pressure and the clinical symptoms. It is emphasized that different other humoral mechanisms may play a role in the pathophysiology of this type of endocrine hypertension. Biochemical tests and non-invasive localizing methods are essential for the definite diagnosis of pheochromocytoma. A great progress has been made in this respect during the last three decades. Surgical removal of the tumor is the only definite therapy with low morbidity and mortality.

Topics: Atrial Natriuretic Factor; Catecholamines; Humans; Hypertension; Neuropeptide Y; Pheochromocytoma; Renin

C-type natriuretic peptide (CNP) in human adrenal glands and adrenal tumors was measured with a specific radioimmunoassay for CNP. Tissue immunoreactive (IR-) CNP concentrations were 0.54 +/- 0.40 pmol/g wet tissue (gwt) (mean +/- SD) in 14 pheochromocytomas, 0.69 +/- 0.19 pmol/gwt in six adrenocortical tumors, and 0.49 +/- 0.22 pmol/gwt in seven normal adrenal glands (cortex and medulla mixed). These concentrations were comparable to those found in tissues from human brains. Sephadex G-50 superfine column chromatography and reverse-phase high performance liquid chromatography revealed that IR-CNP in normal adrenal glands and pheochromocytoma consisted of at least two components: a component in low molecular weight form chromatographically identical to CNP-22 and the other, a high molecular weight form very similar to human CNP-53. This study has shown that IR-CNP is present in human adrenal glands and adrenal tumors with similar molecular forms and comparable concentrations to those in the human brain.

Topics: Adenoma; Adrenal Gland Neoplasms; Adrenal Glands; Aged; Atrial Natriuretic Factor; Chromatography, Gel; Chromatography, High Pressure Liquid; Female; Humans; Male; Middle Aged; Natriuretic Peptide, C-Type; Nerve Tissue Proteins; Pheochromocytoma; Radioimmunoassay

The human heart secretes both atrial natriuretic peptide and brain natriuretic peptide. This study attempts to clarify the pathophysiological significance of the peptides in cardiovascular diseases. Using immunoradiometric assay, plasma brain natriuretic peptide and atrial natriuretic peptide levels in essential hypertension, various secondary hypertension, chronic renal failure, chronic heart failure during cardiac pacing, and acute myocardial infarction were determined. Mean plasma brain natriuretic peptide and atrial natriuretic peptide levels in healthy subjects were 3.7 +/- 0.3 and 5.7 +/- 0.3 pmol/L, respectively, and increased as a function of age. Plasma brain natriuretic peptide levels showed a larger increase than atrial natriuretic peptide levels in various cardiovascular diseases. In chronic renal failure, whereas plasma atrial natriuretic peptide levels decreased significantly after hemodialysis and were correlated with the changes in body weight, changes in plasma brain natriuretic peptide levels were less prominent and did not show such a correlation. In chronic heart failure, both basal plasma brain natriuretic peptide and atrial natriuretic peptide levels were also significantly elevated. However, in response to acute ventricular or atrial pacing, brain natriuretic peptide levels did not show any increase in contrast to the marked increase of atrial natriuretic peptide levels. In acute myocardial infarction, brain natriuretic peptide levels showed more prominent changes than atrial natriuretic peptide levels and were correlated with serum levels of creatine kinase and cardiac myosin light chain I in most patients. These results suggest that both brain and atrial natriuretic peptides play an important role in the regulation of cardiovascular homeostasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adrenal Gland Neoplasms; Adult; Aged; Aging; Atrial Natriuretic Factor; Cardiac Pacing, Artificial; Cardiovascular Diseases; Female; Heart Failure; Humans; Hyperaldosteronism; Hypertension; Kidney Failure, Chronic; Male; Middle Aged; Natriuretic Peptide, Brain; Nerve Tissue Proteins; Pheochromocytoma; Reference Values; Regression Analysis; Renal Dialysis

Peptide hormone synthesis in neuroendocrine tumors is a well-recognized phenomenon. However, production in neuroendocrine tumors of atrial natriuretic polypeptide (ANP), a newly discovered peptide hormone from the heart, has not been studied extensively.. The presence of immunoreactive human ANP (IR-hANP) in neuroendocrine tumors was determined using a specific human ANP radioimmunoassay. Neuroendocrine tumors examined included 9 small cell carcinomas of the uterus, 28 small cell carcinomas of the lung, 20 carcinoid tumors, 54 pancreatic endocrine tumors, 17 neuroblastic tumors, 14 pheochromocytomas, and 14 medullary carcinomas of the thyroid. Twenty atrial tissues also were examined as the control. Molecular size of IR-hANP in the extracts of atrial and tumor tissues was determined by gel chromatography.. IR-hANP was detected in the extracts of small cell carcinoma of the uterus, small cell carcinoma of the lung, and carcinoid tumor, with concentrations ranging from 3.1 to 210 ng/g wet weight tissue. No IR-hANP was detected in the extracts of pancreatic endocrine tumor, neuroblastic tumor, pheochromocytoma, and medullary carcinoma of the thyroid. The frequency of production of IR-hANP in neuroendocrine tumors was highest in small cell carcinoma of the uterus (44%), followed by small cell carcinoma of the lung (18%) and carcinoid tumor (15%). IR-hANP present in the extracts of small cell carcinomas of the uterus had molecular size heterogeneity, with three fragments in addition to alpha-, beta- and gamma-human ANP.. These results indicate that IR-hANP is produced by neuroendocrine tumors and that the molecular size of IR-hANP in tumor tissues is different from that in atrial tissues.

Topics: Atrial Natriuretic Factor; Carcinoid Tumor; Carcinoma, Small Cell; Female; Humans; Lung Neoplasms; Neuroendocrine Tumors; Pancreatic Neoplasms; Pheochromocytoma; Radioimmunoassay; Thyroid Neoplasms; Uterine Neoplasms

The interaction between catecholamines (CA) and ANP is not clearly established. The effects of excess endogenous CA on ANP secretion can be investigated in patients with pheochromocytoma. We studied 27 patients with surgically and histologically proven pheochromocytoma (P) aged 19-70 years. In 16 of these patients plasma ANP study was repeated after surgical removal of the tumour. The control group (C) consisted of 20 healthy volunteers aged 21-48 years. Moreover, 42 patients with uncomplicated mild to moderate essential hypertension (EH) aged 18-48 years were also studied. In P higher plasma ANP concentration versus C, EH was found (51.9 +/- 8.1; 25.5 +/- 1.5; 19.3 +/- 1.5 fmol/ml, respectively). In 16 patients with P, increased plasma ANP level (mean 63.3 +/- 12.6 fmol/ml) declined after surgical removal of the tumour (mean 22.4 +/- 2.9 fmol/ml). In the P patients no relationship was found between plasma ANP and hormonal patterns of the tumour or between plasma ANP and plasma catecholamines, whereas significant positive correlations between plasma ANP and both systolic and diastolic blood pressure and heart rate were demonstrated. These results suggest that excess CA produced by the chromaffin tumour induce ANP secretion via stimulation of adrenergic receptors. However, influence of the haemodynamic changes evoked by CA cannot be excluded. It is suggested that increased secretion of ANP may be of some importance in maintaining blood pressure homeostasis in patients with pheochromocytoma.

Topics: Adrenal Gland Neoplasms; Adult; Aged; Atrial Natriuretic Factor; Catecholamines; Female; Humans; Male; Middle Aged; Pheochromocytoma

Water immersion to the neck is able to provoke a profound suppression of the renin-angiotensin system in several clinical conditions associated with hyper-reninaemia. Both hyper-reninaemia and secondary aldosteronism have sometimes been described in phaeochromocytoma. We report on two patients, with surgically proven phaeochromocytoma, in whom water immersion, performed before surgery, failed to induce any significant change in plasma renin activity.

Topics: Adrenal Gland Neoplasms; Adult; Angiotensin II; Atrial Natriuretic Factor; Blood Pressure; Female; Humans; Immersion; Middle Aged; Pheochromocytoma; Renin; Renin-Angiotensin System

PC12 cells express two atrial-natriuretic-factor-(ANF)-receptor subtypes with molecular masses of 130,000 (B receptor) and 70,000 (C receptor). The B-receptor subtype constitutes 65% of the cell-surface receptor population, and the remaining 35% are C receptors as determined by saturation binding studies in the presence of C-ANF, a C-receptor-selective analogue. ANF-(99-126)-peptide [ANF(99-126)], which can bind to both B- and C-receptor subtypes, was rapidly internalized into the cells after incubation at 37 degrees C. Internalization of 125I-ANF(99-126) was used as an index of the receptor-mediated endocytosis and to quantify receptor internalization. In the presence of a saturating concentration of C-ANF, receptor-mediated internalization of 125I-ANF(99-126) was reduced by 24%, indicating B receptor mediate 76% of ligand internalization. Incubation of cells with 10 microM-ANF at 37 degrees C down-regulated both receptor subtypes as reflected by decreased surface binding. Time-dependent studies suggest that B- and C-receptor subtypes undergo differential down-regulation. Incubation of down-regulated cells for 120 min in ANF-free medium produced a recovery of 35% of the original cell-surface binding. Affinity cross-linking of 125I-ANF to the receptors on the plasma membrane in re-incubated (up-regulated) cells demonstrated expression of predominantly the B-receptor subtype. Monensin blocked 72% of receptor up-regulation, whereas cycloheximide inhibited 43%, suggesting an active recycling mechanism involved in mediating up-regulation of the B receptors. The present study demonstrates a rapid internalization and intracellular recycling mechanism for B receptors in PC12 cells. C receptors also undergo internalization and down-regulation, but recycling of this receptor subtype into the plasma membrane occurs at a lower rate and to a lesser extent than is the case for the B receptor.

Topics: Adrenal Gland Neoplasms; Animals; Atrial Natriuretic Factor; Cell Line; Cell Membrane; Cycloheximide; Cytochalasin B; Down-Regulation; Kinetics; Molecular Weight; Monensin; Peptide Fragments; Pheochromocytoma; Rats; Receptors, Atrial Natriuretic Factor; Receptors, Cell Surface

Analysis of cyclic nucleotide phosphodiesterase (PDE) activity in cellular fractions from cultured rat pheochromocytoma (PC12) cells has shown that the predominant hydrolytic activity in both cytosolic and particulate compartments is characteristic of a PDE II, the cGMP-activatable family of PDE isozymes. Cytosolic PDE activity was purified to a high degree utilizing DE-52 anion exchange and cGMP-Sepharose affinity chromatographies. The physicochemical properties of PC12 PDE II were similar to those of PDE II isolated from particulate or soluble fractions of other tissues, including subunit molecular weight of approximately 102,000, activation of cAMP hydrolysis by cGMP, and positive cooperative kinetic behavior for cAMP and cGMP hydrolysis. The potential role of PDE II in regulating cAMP metabolism in intact PC12 cells was studied using an [3H]adenine prelabeling technique. Stimulation of PC12 cell adenosine receptors resulted in a 5-8-fold increase in cAMP accumulation. Removal of the adenosine stimulus by the addition of exogenous adenosine deaminase resulted in a rapid decay of cAMP to prestimulated basal levels within 2 min. Treatment of PC12 cells with atrial natriuretic factor or sodium nitroprusside caused 1) increased intracellular cGMP levels, 2) attenuation of adenosine-stimulated cAMP accumulation, and 3) increased rates of cAMP decay after removal of the adenosine stimulus. Treatment of PC12 cells with HL-725 (a potent inhibitor of isolated PDE II activity in vitro) caused 1) increased basal cAMP accumulation, 2) potentiation of adenosine-stimulated cAMP accumulation, and 3) retardation of the rate of cAMP decay after removal of the adenosine stimulus. HL-725 blocked both the attenuation of cAMP accumulation and the accelerated rate of cAMP decay observed with the cGMP-elevating agents. These results suggest that, in PC12 cells, drugs or hormones that inhibit PDE II or increase intracellular cGMP levels to activate PDE II can modulate cAMP metabolism by altering the catalytic status of the enzyme.

Topics: 3',5'-Cyclic-GMP Phosphodiesterases; Adenosine; Adrenal Gland Neoplasms; Animals; Atrial Natriuretic Factor; Cyclic AMP; Cyclic GMP; Isoenzymes; Nitroprusside; Pheochromocytoma; Phosphodiesterase Inhibitors; Rats; Tumor Cells, Cultured

Atriopeptin (AP) is expressed in several tissues with each tissue capable of specific differences in processing of the prohormone (pro-AP) to mature low molecular forms of the peptide. Since pro-AP has low biological activity, processing into mature AP is a critical activation event. This observation prompted us to study whether granule storage or regulated secretion of AP is essential for cleavage of mature peptide. We examined the processing of AP in adrenal medulla derived cells, using the rat pheochromocytoma cell line (PC12 cell) stably transfected with a genomic human AP DNA in the presence and absence of nerve growth factor (NGF), and also examined the mechanism of AP secretion and compared the results with those obtained using transfected chinese hamster ovary cells (CHO cells). The amount of prohormone was 5-10 fold higher than that of low molecular form of AP in the transfected PC12 cells. This ratio was essentially unchanged in differentiated PC12 cells after NGF treatment of the cells. Potassium depolarization of the transfected PC12 cells caused a 5-fold increase in AP release into the medium primarily as the intact prohormone. On the other hand, transfected CHO cells only exhibited constitutive AP release which is non-response to depolarization. These results suggest that the AP prohormone is sorted into secretory granules as the prohormone in PC12 cells and undergoes regulated release in response to depolarization indicating granule storage or release is not the critical determinant of AP prohormone cleavage.

Topics: Adrenal Gland Neoplasms; Animals; Atrial Natriuretic Factor; Cell Line; Chromatography, High Pressure Liquid; Cricetinae; Cricetulus; Female; Humans; Immunoenzyme Techniques; Kinetics; Nerve Growth Factors; Ovary; Pheochromocytoma; Plasmids; Potassium Chloride; Protein Precursors; Protein Processing, Post-Translational; Radioimmunoassay; Rats; Restriction Mapping; Transfection

We measured plasma alpha-human atrial natriuretic polypeptide (alpha-hANP) and catecholamine concentrations during anesthesia and surgery for pheochromocytoma in five patients ranging in ages from 19 to 69. Plasma catecholamine concentrations and systemic blood pressure increased extremely during surgical manipulation of the tumor, while plasma alpha-hANP levels did not change even during surgical manipulation or after removal of the tumor as compared with preanesthetic values. Our findings suggest that plasma alpha-hANP levels were unchanged during anesthesia and surgery for human pheochromocytoma.

Topics: Adrenal Gland Neoplasms; Adult; Aged; Atrial Natriuretic Factor; Epinephrine; Female; Humans; Male; Middle Aged; Norepinephrine; Peptide Fragments; Pheochromocytoma

Calcitonin gene-related peptide (CGRP) and atrial natriuretic peptide (ANP) are potent hypotensive agents. To determine if they play a counterregulatory role in catecholamine excess in patients with pheochromocytoma, plasma levels were measured in four patients undergoing resection of sporadically occurring tumors. Each patient was prepared with phenoxybenzamine hydrochloride (Dibenzyline); two patients also received propranolol. Blood was obtained for plasma levels of epinephrine, norepinephrine, CGRP, and ANP at induction of anesthesia, skin incision, tumor manipulation, tumor removal, and 24 hours after operation. Baseline plasma norepinephrine and epinephrine levels were markedly elevated and increased significantly with tumor manipulation and decreased significantly 24 hours after operation. CGRP and ANP levels were slightly elevated throughout but did not change significantly with tumor manipulation or early after tumor resection. Circulating CGRP and ANP do not appear to have an acute counterregulatory role in catecholamine excess in patients with pheochromocytoma but may exert some influence on postoperative hypotension after tumor removal.

Topics: Adrenal Gland Neoplasms; Adult; Atrial Natriuretic Factor; Calcitonin Gene-Related Peptide; Epinephrine; Female; Humans; Middle Aged; Norepinephrine; Pheochromocytoma

Receptor mediated internalization of 125I-ANF (99-126) and the underlying mechanism was studied in PC12 cells. Phosphorylation of PC12 cell plasma membrane proteins at 0 degrees C or 37 degrees C was not altered in presence of ANF (99-126) or c-ANF (4-23). Exposure of cells to phorbol 12-myristate 13-acetate (PMA, 100 ng/ml) did not alter the endocytic rate or extent of 125I-ANF (99-126) internalization. When cells were treated with a combination of PMA and the calcium ionophore A23187, internalization was not stimulated. Incubation with A23187 (10 microM) alone decreased 125I-ANF (99-126) internalization by 22% in Ca2+ containing medium. Cell surface binding increased 10% in the presence of Ca2+ compared to Ca2+ free medium, irrespective of the presence of A23187. Ca2+ appears to play an important role in the binding of ANF to the receptor and initiation of ligand-receptor complex internalization. Activation of protein kinase C or receptor phosphorylation is not an essential step in initiating ANF receptor internalization.

Topics: Adrenal Gland Neoplasms; Animals; Atrial Natriuretic Factor; Calcimycin; Calcium; Cell Membrane; Kinetics; Membrane Proteins; Molecular Weight; Pheochromocytoma; Phosphoproteins; Phosphorylation; Rats; Receptors, Atrial Natriuretic Factor; Receptors, Cell Surface; Tetradecanoylphorbol Acetate

To investigate the possible relationship of hypertension and the N-terminus of the atrial natriuretic factor (ANF) prohormone which contains two peptides [i.e. pro ANF-(1-30) and pro-ANF-(31-67)] with blood pressure-lowering effects, we examined the circulating levels of the N-terminus of the ANF prohormone in three patients with pheochromocytomas before surgery, during an increase in their blood pressure with surgical manipulation of their tumors, and after surgery when their blood pressures returned to normal. The circulating levels of the whole N-terminus [amino acids 1-98; pro-ANF-(1-98)] and pro-ANF-(31-67) from the midportion of the N-terminus of the ANF prohormone were increased 2-fold in patients with both extraadrenal and intraadrenal pheochromocytomas. In both the intraadrenal and extraadrenal patients N-terminus [pro-ANF-(1-98)] and pro-ANF-(31-67) circulating levels increased further during surgical manipulation and returned to normal after surgical removal of their respective tumors. Each of these pheochromocytomas was found to have pro-ANF-(1-30) and -(31-67)-binding sites that were functional, since they could enhance the guanylate cyclase-cGMP system 2-fold in these pheochromocytomas. The entire 126 amino acids of the prohormone were present within each of the pheochromocytomas, since both the whole N-terminus and C-terminus (i.e. ANF) of the prohormone were present. Examination of the pheochromocytomas by electron microscopy revealed electron-dense granules similar to those in the heart, which have been associated with the synthesis and storage of the ANF prohormone. We conclude that 1) the whole N-terminus [pro-ANF-(1-98)] and pro-ANF-(31-67) of the ANF prohormone circulate at higher concentrations in persons with pheochromocytomas and return to normal with removal of the tumors; 2) pheochromocytomas contain specific binding sites for pro-ANF-(1-30) and -(31-67); 3) these binding sites are functional, since pro-ANF-(1-30) and -(31-67) could enhance the enzyme guanylate cyclase within these tumors; and 4) the entire 126 amino acids of the ANF prohormone are present within these tumors, which have electron-dense granules associated with polypeptide hormone synthesis, suggesting that the ANF prohormone is being synthesized within the pheochromocytomas.

Topics: Adolescent; Adrenal Gland Neoplasms; Atrial Natriuretic Factor; Binding Sites; Enzyme Activation; Female; Guanylate Cyclase; Humans; Hypertension; Male; Middle Aged; Peptide Fragments; Pheochromocytoma; Protein Precursors

This study tests the hypothesis that atrial natriuretic factor (ANF) and C-ANF(4-23)-NH2 (C-ANF) augment cGMP generation and inhibit both cAMP generation and depolarization-induced catecholamine release in nerve growth factor treated pheochromocytoma cells by a pertussis toxin (PTX)-sensitive mechanism. Synthetic rat ANF(99-126) and the clearance receptor antagonist C-ANF (10(-12)-10(-9) M) inhibited basal and 5 microM vasoactive intestinal peptide (VIP)-induced cAMP generation in a concentration-dependent manner. These actions of ANF and C-ANF were blocked by 12-18 h pretreatment with PTX (100 ng/ml), suggesting ANF receptor coupling to adenylate cyclase via an inhibitory guanine nucleotide-binding protein. Both ANF (10(-11)-10(-9) M) and C-ANF (10(-11)-10(-8) M) also inhibited K(+)-induced catecholamine release in a concentration-dependent manner. ANF (10(-11)-10(-8) M) increased cGMP generation in a concentration-dependent manner but C-ANF did not. The accumulation of cGMP in response to ANF was not altered by treatment with PTX. Therefore, PTX dissociated the increased concentrations of cGMP from the ANF-mediated depression of evoked catecholamine release. C-ANF also dissociated elevations in cGMP concentrations from an ANF-mediated attenuation of evoked catecholamine release. The results of this study indicate that ANF inhibits adrenergic neurotransmission independent of guanylate cyclase.

Topics: Adenylate Cyclase Toxin; Adrenal Gland Neoplasms; Animals; Atrial Natriuretic Factor; Cyclic AMP; Cyclic GMP; Dopamine; Guanylate Cyclase; Norepinephrine; Pertussis Toxin; Pheochromocytoma; Potassium; Rats; Synaptic Transmission; Tumor Cells, Cultured; Virulence Factors, Bordetella

Clonidine, an agonist of central alpha-2-adrenergic receptors, reduced the peripheral sympathetic activity. With regard to the mutual pathophysiological relationship of blood pressure regulating mechanisms, the authors wanted to find out whether after clonidine administration, in addition to the known suppression of catecholamine levels (CA), also changes in the concentration of other pressor and depressor humoral substances will occur. They investigated therefore in 15 patients with essential hypertension (EH) and in three patients with pheochromocytoma the urinary excretion of free noradrenaline (NA), adrenaline (A) and dopamine (DA), the plasma renin activity (PRA), the aldosterone concentration (PAC) and atrial natriuretic factor (ANF) in plasma, using radioimmunoanalysis, always before and 24 hours after clonidine administration (Haemiton retardR) by the oral route. Its administration led in patients with EH to a decline of NA and DA. On the other hand, in pheochromocytoma their urinary excretion did not change in an unequivocal way, and when it declined, never normal NA and DA levels were reached. A excretion remained unaltered in both groups of patients. The drop of PRA after clonidine as a result of the drop of peripheral adrenergic activity was not associated with an expected parallel drop of PAC but by its rise. This effect can be explained by a reduction of the tonic inhibition of PAC output when the DA level declines. The rise of ANF after clonidine administration will be the subject of subsequent investigations. It cannot be ruled out that this effect is due to the direct action of clonidine on alpha receptors in the heart.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adrenal Gland Neoplasms; Aldosterone; Atrial Natriuretic Factor; Catecholamines; Clonidine; Diagnosis, Differential; Hormones; Humans; Hypertension; Pheochromocytoma; Renin

Using the immunoperoxidase and immunogold methods with specific antibody, we studied the atrial natriuretic polypeptide (ANP) in seven tumor tissues of six patients with adrenal pheochromocytoma. Light microscopically, the reaction product for ANP was observed in all seven tumor tissues. Intracytoplasmic immunoreaction product for ANP was finely granular. In four cases studied with the electron microscope, the immunogold stain for ANP was demonstrated in secretory granules of the tumor cells. A considerable amount of alpha-hANP immunoreactive substance was also extracted from two tumor tissues (67.2 and 28.7 pg/mg wet tissue). This is the first report of the human adrenal pheochromocytoma that contains immunoreactive ANP. These findings provide additional evidence for the multisecretory APUD cells of neural crest origin.

Topics: Adrenal Gland Neoplasms; Adult; Atrial Natriuretic Factor; Female; Humans; Immunohistochemistry; Male; Microscopy, Electron; Middle Aged; Pheochromocytoma

Maitotoxin (MTX) activates calcium channels and stimulates phosphoinositide breakdown in pheochromocytoma PC12 cells, while having no effect on basal levels of the cyclic nucleotides cAMP and cGMP. Atrial natriuretic factor (ANF) induces a dose-dependent accumulation of cGMP in PC12 cells through the activation of a membrane bound guanylate cyclase. Effects of ANF on cGMP are independent of extracellular concentrations of calcium. Since agents that activate phosphoinositide breakdown can indirectly affect cyclic nucleotide formation, the effects of MTX on ANF-mediated accumulation of cGMP was studied. MTX induces a dose-dependent inhibition of ANF-mediated accumulation of cGMP. The inhibition by MTX requires the presence of extracellular calcium, but is unaffected by the calcium channel blocker nifedipine. The inhibitory effect of MTX is not mimicked by the calcium ionophore ionomycin. A phorbol ester, PMA, which stimulates protein kinase C, also inhibits ANF-mediated accumulation of cGMP. Sodium nitroprusside induces large accumulations of cGMP in PC12 cells through the stimulation of a soluble guanylate cyclase. Neither MTX nor PMA inhibit nitroprusside-mediated accumulation of cGMP. The results indicate that in PC12 cells, protein kinase C activation, either directly with PMA, and indirectly with MTX through phosphoinositide breakdown and formation of diacylglycerol, leads to inhibition of ANF-mediated, but not nitroprusside-mediated accumulation of cGMP.

Topics: Atrial Natriuretic Factor; Calcium; Cyclic GMP; Dose-Response Relationship, Drug; Ionomycin; Marine Toxins; Nifedipine; Nitroprusside; Oxocins; Pheochromocytoma; Tetradecanoylphorbol Acetate; Tumor Cells, Cultured

The presence of functional receptors for human atrial natriuretic hormone in human pheochromocytomas was recently reported. The present study reports the binding of hANH as measured by Scatchard analysis in 4 human adrenal glands and in 5 human pheochromocytomas. Binding assays using [3H]ANH revealed a single class of high-affinity binding sites for hANH in both tissues. Human pheochromocytomas present a lower number of binding sites than normal human adrenal gland (Bmax of 7.1 +/- 2.1 vs 33.6 +/- 6.9 fmol/mg protein, respectively). However, the decreased number of ANH receptors was not paralleled by modifications of tissular cyclic GMP (cGMP). Moreover, plasma hANH concentrations in 7 patients with pheochromocytomas (20.2 +/- 2.7 pmol/l) were statistically higher than those obtained in 25 normal control humans (8.1 +/- 0.6 pmol/l, p less than 0.001). We also demonstrated the presence of immunoreactive ANH in the tumour itself.

Topics: Adrenal Gland Neoplasms; Adrenal Glands; Aldosterone; Angiotensin II; Atrial Natriuretic Factor; Binding, Competitive; Chromatography, Ion Exchange; Cyclic GMP; Desoxycorticosterone; Dopamine; Humans; Neuropeptide Y; Pheochromocytoma; Receptors, Atrial Natriuretic Factor; Receptors, Cell Surface; Vasopressins

The effects of synthetic human atrial natriuretic peptide (ANP) on the release of catecholamines, aldosterone, or cortisol were observed in human adrenal tumors obtained surgically from patients with pheochromocytoma, primary aldosteronism, or Cushing's syndrome, respectively. Each tumor tissue or adjacent normal cortical tissue was sectioned into slices, which were incubated in medium-199 in the presence or absence of adrenocorticotrophin (ACTH) and ANP. The amounts of epinephrine, norepinephrine, aldosterone, or cortisol released into the medium were measured. Existence of ANP receptors on the adrenal tissues was examined by binding assays, affinity labeling, and immunohistochemistry. Release of catecholamines from pheochromocytoma tissues was inhibited by ANP, and the presence of the ANP receptor on pheochromocytoma was further demonstrated by both binding assays and affinity labeling; Scatchard analysis revealed a single class of binding sites for ANP with a Kd of 1.0 nM and a Bmax of 0.4 pmol/mg of protein and the molecular size was estimated as 140 and a 70 kDa under nonreducing and reducing conditions, respectively. The presence of ANP receptors in pheochromocytoma was demonstrated by immunohistochemistry. ANP inhibited both basal and ACTH-stimulated aldosterone secretion in the slices of normal cortex, and localization of ANP receptors in zona glomerulosa cells was also demonstrated. However, ANP did not inhibit basal and ACTH-stimulated aldosterone and cortisol secretion in both tissue slices from aldosteronoma and Cushing's adenoma. Consistent with these observations, the absence of ANP receptors in adenoma tissues was determined by binding assays, affinity labeling, and immunohistochemistry.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adrenal Cortex; Adrenal Gland Neoplasms; Atrial Natriuretic Factor; Cell Membrane; Cushing Syndrome; Humans; In Vitro Techniques; Iodine Radioisotopes; Pheochromocytoma; Receptors, Atrial Natriuretic Factor; Receptors, Cell Surface

The effect of synthetic alpha human atrial natriuretic peptide on catecholamine release from human pheochromocytomas was studied both in vivo and in vitro. Iv infusion of atrial natriuretic peptide at a rate of 0.1 microgram.kg-1.min-1 for 60 min into two normotensive patients with pheochromocytoma caused a small decrease in the mean blood pressure, increase in the heart rate, and marked increase in the plasma level of norepinephrine (2.08 to 6.83 nmol/l, and 1.15 to 2.83 nmol/l, respectively) compared with 0.60 +/- 0.10 to 1.19 +/- 0.20 nmol/l in normal subjects. Treatment with atrial natriuretic peptide also increased the plasma epinephrine level from 0.34 to 1.27 nmol/l, and from 0.67 to 0.79 nmol/l in the patients with pheochromocytoma, but not in the normal subjects (0.05 +/- 0.01 to 0.05 +/- 0.01 nmol/l). After removal of the tumour, the responses of the plasma norepinephrine and epinephrine to atrial natriuretic peptide infusion were normalized. There was no significant effect of 10(-8) to 10(-5) mol/l atrial natriuretic peptide on the basal release of catecholamines from isolated superfused pheochromocytoma tissue. Atrial natriuretic peptide (10(-7) mol/l) did not affect the increase in catecholamine release induced by glucagon (10(-5) mol/l). These results suggest that the exaggerated responses of plasma catecholamines to atrial natriuretic peptide in patients with pheochromocytoma may be due to a washout effect resulting from change in blood flow in the vessels feeding the tumour rather than increased sympathetic nerve activity induced by hypotension and hypovolemia. The results also suggest that atrial natriuretic peptide dose not have any direct action on pheochromocytoma tissue causing catecholamine release.

Topics: Adrenal Gland Neoplasms; Adult; Atrial Natriuretic Factor; Epinephrine; Humans; Infusions, Intravenous; Male; Middle Aged; Norepinephrine; Perfusion; Pheochromocytoma

Atrial natriuretic peptide concentrations (ANP) were determined in 4 patients with pheochromocytoma during its surgical removal. There was no correlation among ANP level, plasma catecholamines concentrations and blood pressure. Increase of plasma ANP concentration after tumor removal can be explained by simultaneously observed hypervolemia. It proves that ANP secretion mostly depends on enlarged central blood volume.

Topics: Adrenal Gland Neoplasms; Adult; Atrial Natriuretic Factor; Blood Pressure; Blood Volume; Epinephrine; Humans; Male; Middle Aged; Norepinephrine; Pheochromocytoma

To investigate the possible relationship of atrial natriuretic factor (ANF) to hypertension, we examined the circulating levels of ANF in 3 patients with pheochromocytomas before surgery, during increase of their blood pressure with surgical manipulation of their tumors, and after surgery when their blood pressures returned to normal. The circulating levels of ANF were increased 2-fold in patients with both extra-adrenal and intra-adrenal pheochromocytomas. In both the intra-adrenal and extra-adrenal patients their ANF levels increased further during surgical manipulation and returned to normal after surgical removal of their respective tumors. Each of these pheochromocytomas was examined and found to have atrial natriuretic receptors that were functional since ANF could enhance the guanylate cyclase - cyclic GMP system two-fold in these pheochromocytomas. We conclude that ANF circulates at higher concentrations in persons with pheochromocytomas and returns to normal with removal of the tumor. In addition, pheochromocytomas contain specific ANF receptors and ANF itself within these tumors.

Topics: Adolescent; Adrenal Gland Neoplasms; Atrial Natriuretic Factor; Blood Pressure; Female; Humans; Hypertension; Male; Middle Aged; Pheochromocytoma; Receptors, Atrial Natriuretic Factor; Receptors, Cell Surface

This study tests the hypothesis that atrial natriuretic factor (ANF) inhibits catecholamine release from rat pheochromocytoma cells by increasing levels of intracellular cyclic GMP (cGMP). Rat differentiated pheochromocytoma cells are a model of adrenergic nerves and allow the exploration of the effects of various hormones, autacoids, drugs and neuromodulators on adrenergic neurotransmission in cell culture. Synthetic rat ANF (99-126) inhibited K+-induced norepinephrine and dopamine release, as measured by high-performance liquid chromatography, in a concentration-dependent manner over the concentration range of 10(-11) to 10(-8) M. ANF stimulated intracellular cGMP accumulation, as measured by specific radioimmunoassay, in a concentration-dependent manner over the same concentration range. The cGMP analog, N2-2'-O-dibutyryl cGMP also inhibited K+-induced norepinephrine and dopamine release in a concentration-dependent manner. The results of this study are consistent with the hypothesis that ANF acts as an inhibitory neuromodulator in adrenergic nerves via the second messenger, cGMP.

Topics: Animals; Atrial Natriuretic Factor; Catecholamines; Cyclic GMP; Dibutyryl Cyclic GMP; Pheochromocytoma; Potassium; Rats; Tumor Cells, Cultured

Specific receptors for atrial natriuretic factor (ANF) are characterized on PC12 cells (rat pheochromocytoma cell line). Radioiodinated synthetic ANF (Rat, 8-33) bound to a single class of high affinity binding sites with the Kd value of 6.7 X 10(-10) M. The Bmax value was 29 fmol/10(5) cells and receptor density was calculated as 194,000 +/- 20,000/cell. Photoaffinity labelling of ANF receptor specifically labelled two protein bands with apparent m.wt of 70,000 and 130,000. When the cells were incubated with the labelled ligand at 37 degrees C the ligand was internalized. The rate of internalization increased in the presence of increased ligand concentration. ANF receptors on PC12 cells are reported for the first time which would provide a unique model for study of ANF-receptor interaction.

Topics: Adrenal Gland Neoplasms; Affinity Labels; Animals; Atrial Natriuretic Factor; Cell Line; Cell Membrane; Kinetics; Molecular Weight; Pheochromocytoma; Receptors, Atrial Natriuretic Factor; Receptors, Cell Surface; Succinimides

Specific binding sites for atrial natriuretic peptide have been identified in membrane of the phaeochromocytoma cell line PC12. Scatchard analysis of binding studies revealed a Kd of 794 pM and a density (Bmax) of 254 fmol/mg protein. Hormones unrelated to ANP such as angiotensin II, bradykinin and arginine-8-vasopressin did not complete for the binding sites. Of the ANP-related peptides which competed for the binding sites, the following order of affinity was established; rANP (8-33) greater than rANP (28 amino acid) greater than rat atrial peptide fragment (13-28) greater than a-hANP (28 amino acid) greater than atrial peptide fragment (1-11) greater than atriopeptin I.

Topics: Adrenal Gland Neoplasms; Animals; Atrial Natriuretic Factor; Binding, Competitive; Cell Line; Cell Membrane; Kinetics; Pheochromocytoma; Rats; Receptors, Atrial Natriuretic Factor; Receptors, Cell Surface

Topics: Adrenal Gland Neoplasms; Atrial Natriuretic Factor; Catecholamines; Female; Humans; Intraoperative Period; Middle Aged; Multiple Endocrine Neoplasia; Pheochromocytoma

Evidence for a presynaptic neuromodulatory effect of atrial natriuretic factor (ANF) has been obtained in rat adrenal pheochromocytoma cells (PC12), a clonal line that differentiates into adrenergic neuron-like cells when treated with nerve growth factor. ANF had no effect on basal norepinephrine (NE) release. In contrast, ANF markedly and significantly inhibited carbachol-induced NE release in a concentration-dependent manner. This result is consistent with the hypothesis that ANF may be an inhibitory neuromodulator.

Topics: Adrenal Gland Neoplasms; Animals; Atrial Natriuretic Factor; Carbachol; Norepinephrine; Pheochromocytoma; Rats; Sympathetic Nervous System; Tumor Cells, Cultured

Using two radio-immunoassays for N-terminal and C-terminal fragments of human atrial natriuretic polypeptide (ANP) precursor, gamma-hANP [human atrial natriuretic factor-(1-126)], that is gamma-hANP(1-25) [human atrial natriuretic factor-(1-25)] and alpha-hANP [human atrial natriuretic factor-(99-126)], we studied the secretion of gamma-hANP-derived peptides into circulation from the heart in normal subjects and patients with essential hypertension and adrenal disorders. Volume expansion with 2 litres physiological saline increased plasma gamma-hANP(1-25)-like immunoreactivity concomitantly with plasma alpha-hANP-like immunoreactivity in normal subjects. Infusion of angiotensin II (20 ng/kg per min) or noradrenaline (200 ng/kg per min) also caused a parallel increase in plasma gamma-hANP(1-25)-like and alpha-hANP-like immunoreactivity. Plasma gamma-hANP(1-25)-like immunoreactivity levels were changed together with alpha-hANP-like immunoreactivity in patients with essential hypertension and adrenal disorders. These results indicate that gamma-hANP-derived peptides, alpha-hANP and the 10-k N-terminal fragment of gamma-hANP (N-peptide) are cosecreted from the heart and that the simultaneous measurement of N-peptide and alpha-hANP serves as an indicator of the cardiac endocrine function. The significance of N-peptide as a hormone must await further clarification.

Topics: Addison Disease; Adrenal Gland Diseases; Adrenal Gland Neoplasms; Angiotensin II; Atrial Natriuretic Factor; Blood Volume; Cushing Syndrome; Humans; Hyperaldosteronism; Hypertension; Immunoassay; Pheochromocytoma

Atrial natriuretic factors (ANFs) were tested for their effects on cyclic GMP production in two neurally derived cell lines, the C6-2B rat glioma cells and the PC12 rat pheochromocytoma cells. These cell lines were selected because both are known to possess high amounts of the particulate form of guanylate cyclase, a proposed target of ANF in peripheral organs. Previous studies from our laboratory have shown that ANF selectively activates particulate, but not soluble, guanylate cyclase in homogenates of a variety of rat tissues and that one class of ANF receptor appears to be the same glycoprotein as particulate guanylate cyclase. In the present study we found that four analogs of ANF stimulate cyclic GMP accumulation in both C6-2B and PC12 cells with the rank order of potency being atriopeptin III = atriopeptin II greater than human atrial natriuretic polypeptide greater than atriopeptin I. Atriopeptin II (100 nM) for 20 min elevated cyclic GMP content in C6-2B cells fourfold and in PC12 cells 12-fold. Atriopeptin II (100 nM) for 20 min also stimulated the efflux of cyclic GMP from both C6-2B cells (47-fold) and PC12 cells (12-fold). Accumulation of cyclic GMP in both cells and media was enhanced by preincubation with the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (250 microM). After 20 min of exposure to atriopeptin II, cyclic GMP amounts in the media were equal to or greater than the amounts in the cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 1-Methyl-3-isobutylxanthine; Adrenal Gland Neoplasms; Animals; Atrial Natriuretic Factor; Cell Line; Cyclic GMP; Dose-Response Relationship, Drug; Glioma; Pheochromocytoma; Rats; Time Factors

Pheochromocytoma, a catecholamine-secreting adrenomedullary tumor, has been shown to contain the functional receptor for human atrial natriuretic peptide(h-ANP). Release of catecholamines from tissue slices of pheochromocytoma was inhibited by h-ANP in a dose-dependent manner. Binding assays using 125I-ANP revealed a single class of high affinity binding sites for ANP. When covalently tagged with 125I-ANP and electrophoresed under non-reducing and reducing conditions, the receptor migrated as a 140-kDa band and a 70-kDa band, respectively, reflecting its disulfide-linked subunit structure. The presence of ANP receptor in pheochromocytoma was further demonstrated by immunohistochemistry; the tumor was positively stained with an antireceptor antiserum. The antiserum was also useful to establish the zona glomerulosa localization of ANP receptor in the normal human adrenal gland.

Topics: Adrenal Gland Neoplasms; Atrial Natriuretic Factor; Epinephrine; Humans; In Vitro Techniques; Kinetics; Norepinephrine; Pheochromocytoma; Receptors, Atrial Natriuretic Factor; Receptors, Cell Surface

1. A significant positive correlation was found between changes in circulating noradrenaline (NA) levels and changes in atrial natriuretic peptide (ANP) levels during NA infusion and clonidine administration. 2. A significant positive correlation was also found between changes in arterial blood pressure and changes in ANP level during infusion of angiotensin II and of NA. 3. Two patients with very high circulating NA levels due to phaeochromocytoma, but receiving alpha- and beta-blockade, did not have clearly elevated ANP. A third not receiving medications and aged 73 years had elevated levels. 4. Atrial natriuretic peptide response to NA and angiotensin II may be mediated by changes in blood pressure levels or increased noradrenergic and angiotensinergic receptor activity in the atria or both. Atrial natriuretic peptide may have a role in blood pressure regulation in both normotensive and hypertensive man.

Topics: Adolescent; Adrenal Gland Neoplasms; Adult; Aged; Angiotensin II; Atrial Natriuretic Factor; Clonidine; Humans; Hypertension; Infusions, Intravenous; Middle Aged; Norepinephrine; Pheochromocytoma

Topics: Adenoma; Adrenal Gland Neoplasms; Atrial Natriuretic Factor; Cushing Syndrome; Humans; Hyperaldosteronism; Pheochromocytoma; Pituitary Neoplasms