Compelling evidence indicates that the endothelium-derived potent vasoconstrictor endothelin-1 (ET-1) stimulates aldosterone secretion by interacting with specific receptors. Although two different ET-1 receptors have been identified and cloned, the receptor subtype involved in mediating aldosterone secretion is still unknown. Accordingly, we wished to investigate whether the genes of ET-1 and of its receptors A and B are expressed in the normal human adrenal cortex. We designed specific primers for ET-1 and the ETA and ETB receptors genes and developed a reverse transcription polymerase chain reaction (RT-PCR) with chemiluminescent quantitation of the cDNA. In addition, we carried out 'I ET-1 displacement studies with cold ET-1, ET-3 and the specific ETA and ETB ligands BQ123 and sarafotoxin 6C. Localization of each receptor subtype was also investigated by autoradiography. Binding experiments were first individually analyzed by Scatchard and Hofstee plot and then coanalyzed by the nonlinear iterative curve fitting program Ligand. Histologically normal adrenal cortex tissue, obtained from kidney cancer patients (n = 7), and an aldosterone-producing adenoma (APA), which is histogenetically derived from the zona glomerulosa (ZG) cells, were studied. Results showed that the ET-1, ETA and ETB mRNA can be detected by RT-PCR in all adrenal cortices as well as in the APA. The best fitting of the 125I ET-1 displacement binding data was consistently provided by a two-site model both in the normal adrenal cortex (F = 22.1, P < 0.0001) and in the APA (F = 18.4, P < 0.0001). In the former the density (B..n) of the ETA and ETB subtype was 2.6±0.5 pmol/mg protein (m±SEM) and 1.19±0.6, respectively. The dissociation constant (Kd) of ET-1, S6C,

High renin hypertension has been associated with a higher risk of stroke than low-to-normal renin hypertension. Accordingly, we investigated prospectively the prevalence of the extracranial carotid artery lesions in a case-control study of 70 patients (38 women and 32 men, aged 16 to 77 years) without history or symptoms of cerebrovascular disease. Renovascular hypertension was diagnosed in 35 patients on the basis of the angiographic demonstration of renal artery stenosis and of the favorable outcome after revascularization. It was caused by atherosclerosis in 20 patients and by fibrodysplasia in 15. Each renovascular hypertensive patient was individually matched with a control with primary hypertension for sex, race, age, blood pressure levels, duration of hypertension, smoking, diabetes mellitus, total serum cholesterol, and triglycerides. Carotid arteries were evaluated by a High Resolution Duplex system (Biosound 2000, probe 4 cm, 8 mHz). Our results show that after the matching the two groups were similar in terms of demographic features and overall cardiovascular risk profile (all P = NS). In renovascular hypertensives the prevalence of carotid artery lesions (82.6%) was significantly (P less than .01) higher than in primary hypertensives (42.9%). The higher prevalence of lesions in renovascular hypertension was observed not only in patients with atherosclerosis (100% v 55%, P less than .001), but also in those with fibrodysplasia (57% v 27%, P less than .01). Thus, for the same demographic features and overall cardiovascular risk profile, renovascular hypertension carries a more detrimental effect on the carotid artery than primary hypertension.

Endothelin-1 stimulates aldosterone secretion by interacting with specific receptors. Accordingly, we wished to investigate endothelin-1, endothelin-A (ETA) receptor, and endothelin-B (ETB) receptor gene expression, localization, and properties in aldosterone-producing adenomas and in the normal human adrenal cortex. We carried out 125I-endothelin-1 displacement studies with cold endothelin-1, endothelin-3, the specific ETA antagonist BQ-123, and the specific ETB weak agonist sarafotoxin 6 C and coanalyzed data with the nonlinear iterative curve-fitting program LIGAND. We also studied gene expression with reverse transcription-polymerase chain reaction with specific primers for endothelin-1, ETA, and ETB complementary DNA. Normal adrenal cortices from consenting kidney cancer patients (n = 2) and aldosterone-producing adenomas (n = 4) were studied; for the latter, surrounding normal cortex and kidney biopsy tissue served as controls. To further localize the receptor subtypes, tissue sections were studied by autoradiography in the presence and absence of 500 nmol/L BQ-123, 100 nmol/L sarafotoxin 6 C, and 1 mumol/L cold endothelin-1. In all tissues examined, endothelin-1, ETA, and ETB messenger RNAs were easily detected. However, in aldosterone-producing adenomas, both receptors' genes were expressed at a higher level than in the kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

To investigate whether the 24-hour blood pressure (BP) profile of primary aldosteronism differs from that of primary hypertension, ambulatory BP monitoring was performed in 11 patients with primary aldosteronism (9 with an adrenal adenoma and 2 with idiopathic hyperaldosteronism) and in 11 primary hypertensives, matched for sex (5M,6F), age (mean: 52 vs 49 yrs) and casual BP. We found no difference in 24-hour BP, nocturnal BP fall, BP variability (standard deviation and peaks of pressure) response to postural changes (lying-standing BP) between the two groups (all p values n.s.). Within the patients with primary aldosteronism no correlation was observed between BP, plasma renin activity, blood and urine aldosterone levels, blood and urine K+, and size of the tumour. Thus, at variance with previous reports, these results show that diurnal rhythm of BP and BP variability are similar in primary aldosteronism and primary hypertensives with similar demographic features and causal BP levels. They also show that an orthostatic fall of BP is not a common feature in this disease.

Renovascular hypertension and high renin hypertension were found to be associated with an excess prevalence of carotid artery atherosclerotic lesions and to a higher risk of stroke, respectively, as compared to low-to-normal renin hypertension. Primary aldosteronism, being characterized by hypertension and a chronically suppressed plasma renin activity, should be accompanied by a low prevalence of carotid artery lesions. To verify this hypothesis we investigated prospectively, by a high resolution duplex ultrasound technique, the prevalence of extracranial carotid artery lesions in a case-controlled study of 34 (22 women and 12 men, aged 22 to 76 years) patients with no history or symptoms of cerebrovascular disease. Primary aldosteronism was diagnosed in 17 patients; 12 had a surgically confirmed unilateral aldosterone-secreting adenoma; and 5 had idiopathic hyperaldosteronism. Each primary aldosteronism patient was individually matched with a control with primary hypertension for sex, race, age, body mass index, casual blood pressure levels, duration of hypertension, smoking, diabetes mellitus, total serum cholesterol, and triglycerides. After the matching, the two groups were similar in terms of demographic features and overall cardiovascular risk profile (all P = NS). However, plasma renin activity and aldosterone levels were significantly lower and higher, respectively, in primary aldosteronism than in primary hypertensive patients. In primary aldosteronism the overall prevalence of carotid artery lesions at duplex was 59%, not significantly different from that (53%) found in primary hypertensives. Thus, at variance with renovascular hypertension, primary aldosteronism is not associated with an excess prevalence of carotid artery lesions.

A case of renin-secreting juxtaglomerular cell tumour which presented with a severe hypertensive crisis and did not respond to angiotensin converting enzyme inhibitors but was promptly controlled by intravenous labetalol is reported. The diagnostic difficulties which can be encountered in such cases and the usefulness of the different diagnostic tests, including renal vein renin measurement, are discussed.

The diagnosis of phaeochromocytoma is sometimes difficult since its clinical presentation is quite variable. We report a 52-year-old woman who presented with acute diabetes mellitus and severe hypertension, which spontaneously disappeared. MIBG-scintigraphy and urine and plasma catecholamines were normal. At surgery, a largely necrotic phaeochromocytoma was found. Pathological examination demonstrated extensive avascular necrosis, which had occurred spontaneously without any major symptoms.

Endothelin-l (ET-1) is a 21-amino acid peptide secreted by endothelial cells, that exerts a potent vasoconstrictor action. Two subtypes of ET-1 receptors have been recently identified: ETA and ETB, which are expressed by vascular smooth-muscle cells and endothelium, respectively. Compelling evidence indicates that ET-1 exerts a strong secretagogue effect on adrenal zona glomerulosa (ZG), but not zona fasciculata (ZF) in vivo and in vino; therefore, We performed an autoradiographic study of the occurrence of ET-1 receptors in the human adrenal cortex. 1251-ET-1 binding was intense in the ZG and weak in the ZE, where it was clearly confined to the endothelial lining of capillaries. BQ-123, a selective antagonist of ETA, markedly attenuated 1251-ET-l labeling in ZG, Without affecting that in ZF; conversely, sarafotoxin 6C, a selective ligand of ETB, caused a moderate attenuation of 1251-ET-1 binding in the ZG and, as expected, completely eliminated it in ZF. In light of these findings the conclusion is drawn that human ZG parenchymal cells possess specific ET-1 receptors, being probably able to express both ETA and ETB receptor subtypes.