Benign and malignant hypertension after adrenal enucleation in the rat. Relationship to salt intake, response to hydrochlorothiazide, and similarity to essential hypertension.

Adrenal-enucleated, mononephrectomized rats given a high salt diet rapidly develop malignant hypertension, characterized by the presence of necrotizing vascular lesions in a number of organs and tissues. If a normal salt intake is provided, or if hydrochlorothiazide is given together with a high salt diet, there is, instead, the delayed onset of benign hypertension which either stabilizes or increases in intensity extremely slowly; Such animals display few, if any, pathologic vascular changes other than occasional focal glomerular hyalinization, show insignificant cardiac enlargement, and do not exhibit alterations in the serum sodium or potassium. Occasional animals behave atypically and develop malignant hypertension despite normal salt consumption, demonstrating that in susceptible rats excess salt is not essential to this disorder. Hydrochlorothiazide given to rats that imbibed distilled water postoperatively prevented hypertension entirely for 97 days, when one of eight rats developed mild hypertension and some others reached what is regarded as a prehypertensive range. It is concluded that adrenal regeneration provides a physiological milieu favorable to the development of benign hypertension, which is not, as a rule, manifest until regeneration is complete. Salt excess converts the response into one in which malignant hypertension begins during regeneration and worsens rapidly thereafter until death. The course and findings are compared with those of the benign and malignant phases of clinical essential hypertension, and the implications of the similarities are discussed.

Urinary kallikrein excretion in essential and mineralocorticoid hypertension.

Urinary kallikrein excretion has been reported to be decreased in patients with essential hypertension and elevated in patients with primary aldosteronism as a reflection of mineralocorticoid activity. Low renin essential hypertension (LREH) has been postulated to result from excess production of an unknown mineralocorticoid(s). Urinary kallikrein excretion was compared in outpatients with essential hypertension, mineralocorticoid hypertension (primary aldosteronism and 17alpha-hydroxylase deficiency), and in normal subjects of the same race. No significant difference in urinary kallikrein excretion of patients with LREH vs. normal renin essential hypertension (NREH) was found for either black (4.1+/-0.4 vs. 4.8+/-0.5 esterase units (EU)/24 h, mean+/-SE, for 27 LREH and 38 NREH, respectively) or white patients (12.2+/-2.3 vs. 11.7+/-1.4 EU/24 h for 13 LREH and 25 NREH, respectively). Urinary kallikrein was decreased in black vs. white hypertensive patients and normal subjects. However, in patients with normal renal function (creatinine clearance >/=80 ml/min) urinary kallikrein was not significantly decreased in either black hypertensive vs. black normal subjects (4.3+/-0.3 vs. 5.4+/-0.6 EU/24 h) or in white hypertensive vs. white normal subjects (11.9+/-1.2 vs. 8.4+/-0.9 EU/24 h). In contrast, hypertensive patients with mild renal insufficiency (creatinine clearance of 41.8+/-78.5 ml/min) had reduced (P < 0.05) urinary kallikrein (3.3 EU/24 h with creatinine clearance of 63.6+/-2.0 for 24 black patients and 4.2+/-0.7 EU/24 h with creatinine clearance of 67.0+/-3.5 for 6 white patients). These results suggest that a reduction in urinary kallikrein excretion rate is an early accompaniment of hypertensive renal injury. Urinary kallikrein excretion in response to a 6-d 10-meq sodium diet and a 3-d Florinef (0.5 mg b.i.d.) administration was compared in hypertensive patients with normal renal function vs. race and age-matched normal subjects. Stimulation of urinary kallikrein excretion by Florinef was equal in black and white normal subjects vs. hypertensive patients (black normals = 12.3+/-2.7 [n = 9], NREH = 11.7+/-1.8 [n = 10], LREH = 10.9+/-1.5 [n = 12]; white normals = 21.2+/-2.9 [n = 11], essential hypertension = 20.9+/-3.2 [10 NREH, 5 LREH]). Stimulation of urinary kallikrein excretion with low sodium diet was decreased (P < 0.05) only in black LREH (black normals = 11.2+/-2.4 [n = 10], NREH = 10.1+/-2.7 [n = 10], LREH = 7.4+/-1.1 [n = 13]; white normals = 19.1+/-2.7 [n = 13], essential hypertension = 17.5+/-2.3 [nine NREH, four LREH]). However, during low sodium diet, black patients with LREH had evidence for less sodium depletion as manifested by a decreased rise in urinary aldosterone excretion (16.3+/-2.7 vs. 33.3+/-6.4 mug/24 h for black normals) and a failure to achieve metabolic balance in 11/13 patients. Thus, the lesser kallikrein stimulation appeared to result from these two factors. Black and white hypertensives with creatinine clearance <80 ml/min had little increase in urinary kallikrein excretion with Florinef or low sodium diet.5 of 12 patients with primary aldosteronism or 17alpha-hydroxylase deficiency did not have an elevated urinary kallikrein excretion rate. Mild renal insufficiency may have contributed to this finding in two of these five patients. Nevertheless, this finding illustrates a limitation to the use of urinary kallikrein excretion rate as an index of mineralocorticoid activity. However, it appears that the majority of patients with LREH have no evidence for excess production of an unknown mineralocorticoid. The failure to find a decrease in urinary kallikrein excretion in racially matched patients with essentil hypertension and normal renal function questions the postulate of a role of the kallikrein-kinin system in the initiation of essential hypertension.

Aldosterone suppression with dopamine infusion in low-renin hypertension.

A dopaminergic mechanism has been proposed to suppress aldosterone secretion. To assess the possibility that a defect in the dopaminergic mechanism might enhance aldosterone secretion in hypertensive patients, we determined basal and adrenocorticotropic hormone (ACTH)-stimulated plasma aldosterone (PA), cortisol, renin activity, and potassium concentrations before and during dopamine receptor stimulation with dopamine infusion and bromocriptine administration and dopamine receptor blockade with metoclopramide. The patient study groups included: (a) seven patients with low-renin hypertension and abnormal aldosterone suppression with sodium loading and presumed bilateral zona glomerulosa hyperplasia (ZGHP); (b) two patients with aldosterone-producing adenoma; (c) five patients with low-renin hypertension but normal aldosterone suppression with sodium loading; and (d) six patients with normal-renin hypertension. Dopamine infusion in patients with ZGHP caused PA to fall (P less than 0.01) into the normal range, but did not block the enhanced (P less than 0.05) aldosterone response to ACTH that is characteristic of these patients. Dopamine infusion in patients with low-renin hypertension but normal aldosterone suppression also suppressed PA (P less than 0.01), whereas it had no effect upon PA in patients with normal-renin hypertension or aldosterone-producing adenoma and did not blunt the PA response to ACTH in either group. Bromocriptine administration had no effect upon basal or ACTH-stimulated PA. Dopamine infusion in patients with ZGHP also enhanced (P less than 0.05) diuresis and natriuresis in comparison with normal-renin patients. Metoclopramide administration increased (P less than 0.01) PA in all patients. Thus, a dopaminergic mechanism appears to be important in the regulation of aldosterone secretion in patients with ZGHP and in other low-renin hypertensives with normal aldosterone suppression with sodium loading. In contrast, this latter group does not exhibit an enhanced aldosterone response to ACTH. Both of these groups differ from normal-renin hypertensives, who have no PA suppression with dopamine infusion.

Combination of converting enzyme inhibitor with diuretic for the treatment of hypertension.

In recent years there has been increased discussion about goals of antihypertensive therapy other than blood pressure reduction. The development of angiotensin-converting enzyme inhibitors has provided a class of drugs with a very low side-effect profile. However, single-drug therapy is effective in only about half of hypertensive patients. In the past, diuretics have traditionally been used as the initial or second antihypertensive. Increasingly, diuretic therapy is being avoided, and other antihypertensive combinations are being used. In controlled trials, combination converting enzyme inhibitor-diuretic therapy is effective in about 85% of patients. This synergistic combination allows the diuretic dose to be reduced so that the adverse effects and metabolic complications are minimized. At this time, the combination of converting enzyme inhibitor and diuretic provides an ideal choice in terms of efficacy, compliance, side effects, and cost.

Role of renin classification for diuretic treatment of black hypertensive patients.

Previous studies in white and mixed-race hypertensive patient populations have generally found patients with low renin activity more responsive to diuretic therapy than patients with normal renin activity. Twenty-nine black patients (26 women and three men) with placebo diastolic blood pressure of 90 to 115 mm Hg were treated with spironolactone (100 to 400 mg/day) and hydrochlorothiazide (100/mg/day). Renin status was categorized by (1) the intravenous furosemide test, (2) ambulation during placebo, and (3) ambulation during spironolactone and hydrochlorothiazide treatment. Only seven patients were categorized identically with all methods. No method identified a low renin subgroup that was more responsive to either spironolactone or hydrochlorothiazide. Diastolic blood pressure fall with hydrochlorothiazide (18 mm Hg) and 400 mg/day of spironolactone (15 mm Hg) was similar. Thus, since black women with both low and normal renin activity are quite responsive to diuretics, renin classification to guide initial antihypertensive selection is not warranted.

Antihypertensive comparison of furosemide with hydrochlorothiazide for black patients.

Furosemide and hydrochlorothiazide were compared for treatment of black patients with mild to moderate hypertension in a randomized, open-label, crossover study design. Hydrochlorothiazide produced a significantly greater fall in mean arterial (24.7 vs 16.0 mm Hg, P less than .01) and diastolic (17.3 vs 10.1 mm Hg, P less than .01) blood pressure (BP) in 16 patients. Addition of methyldopa in nine patients produced a significantly greater fall in mean arterial (38.8 vs 31.9 mm Hg, P less than .05) and diastolic (28.9 vs 23.4 mm Hg, P less than .05) BP with hydrochlorothiazide vs furosemide. Renin status was categorized before and after treatment. Patients with low and normal renin activity were equally responsive to both diuretics. Hydrochlorothiazide caused a greater reduction in plasma potassium (0.26 mEg/L). Serum parathyroid hormone was not chronically elevated with furosemide. In this study, hydrochlorothiazide was more effective than furosemide for treatment of mild to moderate hypertension in black patients; renin classification did not predict diuretic responsiveness.

Metabolic effects of hydrochlorothiazide and enalapril during treatment of the hypertensive diabetic patient. Enalapril for hypertensive diabetics.

To determine the effect of enalapril maleate and low-dose hydrochlorothiazide therapy on blood pressure and glucose and lipid homeostasis in hypertensive type II diabetic patients, we treated nine of these patients sequentially with placebo, hydrochlorothiazide (25 mg/d with supplemental potassium chloride), and enalapril (10 to 20 mg/d). Sitting blood pressure fell significantly and to comparable levels with both hydrochlorothiazide and enalapril monotherapy. Enalapril monotherapy was associated with a slight, but not significant, fall in fasting blood glucose levels and with a significant fall in hemoglobin A1c levels. This improved glucose homeostasis could not be explained satisfactorily by changes in peripheral insulin sensitivity or hepatic glucose output, determined with the euglycemic clamp technique, or by changes in fasting serum insulin levels or monocyte insulin binding. In these low doses, hydrochlorothiazide did not worsen glucose homeostasis. Serum total cholesterol levels were significantly lower with enalapril therapy than with hydrochlorothiazide therapy or with placebo, and serum high-density lipoprotein cholesterol and triglyceride levels did not change significantly with either treatment. Thus, by providing effective blood pressure control and beneficial metabolic effects, enalapril therapy appears ideal for treatment of hypertension in diabetic patients. Similarly, low-dose hydrochlorothiazide therapy appears to have fewer metabolic complications in these patients and is, therefore, a logical alternative to substitute for, or add to, enalapril therapy.

Single-voided urine metanephrine assays in screening for pheochromocytoma.

To facilitate the screening for pheochromocytoma, we have validated the use of single-voided, spot urine specimens for the determination of total metanephrines. Metanephrine excretion was found to be quite constant throughout the day and night in ten patients with essential hypertension and seven patients with pheochromocytoma. The levels in single-voided specimens were closely correlated to those in 24-hour specimens in 100 hypertensive subjects. The mean +/- 2 SD metanephrine excretion in single-voided urine specimens from 500 hypertensive subjects was 0.351 +/- 0.356 mug/mg of creatinine.

Modulation of aldosterone synthase messenger ribonucleic acid levels by dietary sodium and potassium and by adrenocorticotropin.

Recent evidence suggests that an aldosterone synthase (AS) separate from the 11 beta-hydroxylase (11 beta-OHase) mediates the final step(s) in aldosterone synthesis in the rat. We have compared changes in AS and 11 beta-OHase mRNA levels with experimental maneuvers known to stimulate or suppress aldosterone secretion. In Exp 1, male rats were fed regular rat chow (group 1), a low sodium, high potassium diet (group 2), or a high sodium, low potassium diet (group 3). Northern analysis of adrenal capsular (zona glomerulosa) and decapsulated adrenal core (fasciculata-reticularis) tissues was performed with specific oligonucleotide probes for AS and 11 beta-OHase mRNAs, normalized with a cDNA probe for 18S ribosomal RNA (rRNA). There was a marked increase in capsular AS mRNA in group 2 rats compared to levels in group 1 (P < 0.0001) and group 3 (P < 0.0001) rats. Capsular As mRNA decreased (P < 0.05) in group 3 compared to that in group 1 rats. Adrenal core AS mRNA levels were quite low with all three diets. In contrast, capsular and core 11 beta-OHase mRNA levels did not change significantly with diet. In Exp 2, two groups served as controls (groups 1 and 3), and two groups received sc injections of repository ACTH (groups 2 and 4). Control and ACTH-treated rats were killed 3 h (groups 1 and 2) or 24 h (groups 3 and 4) after initial ACTH administration. Capsular and core AS and 11 beta-OHase mRNA levels were evaluated with and without normalization with 18S rRNA, cyclophilin, and glyceraldehyde phosphate dehydrogenase housekeeping probes. Capsular AS mRNA increased at 3 h (P < 0.05), but decreased at 24 h (P < 0.01). Nonnormalized adrenal capsular and core 11 beta-OHase mRNA levels were unchanged at 3 h, but increased significantly at 24 h (P < 0.05) in capsular tissue of ACTH-treated rats. However, in ACTH-treated rats, 18S rRNA and cyclophilin mRNA levels increased at 24 h in both capsular and core tissue (P < 0.01), and glyceraldehyde phosphate dehydrogenase mRNA levels increased in capsular tissue (P < 0.00001), resulting in a lack of change in normalized 11 beta-OHase mRNA. Changes in cholesterol side-chain cleavage were similar to those in 11 beta-OHase mRNA. These data provide further evidence that a separate AS plays a significant role in modulating aldosterone secretion in rodents.

Circadian rhythms of serum renin activity and serum corticosterone, prolactin, and aldosterone concentrations in the male rat on normal and low-sodium diets.

To investigate the control of aldosterone secretion, non-stress levels of serum aldosterone, corticosterone, and prolactin, and renin activity were determined at 4-h intervals during 24-h light-dark cycles in adult male rats on regular and low-sodium diets. Circadian rhythms of plasma aldosterone, prolactin, and corticosterone concentrations and of serum renin activity were demonstrated during a regular sodium diet. When the rats were on a low-sodium diet, a circadian rhythm of serum corticosterone and aldosterone concentration was observed, but there was no circadian variation in serum renin activity or in serum prolactin concentration. Serum aldosterone concentration correlated with serum corticosterone concentration (r = 0.48) and serum renin activity (r = 0.36) during a low-sodium diet. Serum prolactin concentration did not correlate with serum aldosterone concentration or serum osmolality. These data are compatible with a role for renin and ACTH, but not for prolactin, in the modulation of aldosterone secretion in the rat.

Influence of 19-nor-deoxycorticosterone on blood pressure, saline consumption, and serum electrolytes, corticosterone, and renin activity.

Young, unilaterally nephrectomized, female Sprague-Dawley rats were given daily sc injections of 19-nor-deoxycorticosterone acetate (19-nor-DOCA) in oil at a dosage of 100 micrograms/day for 21 days and twice that amount for a further 11 days. One group drank distilled water and another drank 1% NaCl solution. Comparable control groups received oil injections. Another group received DOCA at the same steroid dosage and drank saline. Both 19-nor-DOCA-treated groups rapidly became hypertensive and developed cardiac hypertrophy, as did those given DOCA and saline. Saline consumption was greater in rats receiving 19-nor-DOCA, than in those given DOCA. Rats injected with 19-nor-DOCA and given water to drink showed enhanced growth and developed thymus enlargement and displayed hypokalemia and a reduction in both serum renin activity and corticosterone concentration. Plasma sodium concentration was not affected by any form of treatment. Clearly, 19-nor-DOCA is a potent mineralocorticoid and hypertensogenic agent. Since the parent steroid is known to be present abundantly in the urine of rats with regenerating adrenal glands, although circulating amounts have not yet been ascertained in that circumstance, it may be etiologically involved in adrenal regeneration hypertension, which such rats are prone to develop.

Experimental hypertension and other responses to 18-hydroxy-deoxycorticosterone treatment in the rat.

Young female unilaterally nephrectomized, salt-loaded, Sprague-Dawley rats were treated with 200 microgram or 1 mg 18-hydroxy-deoxycorticosterone-21-acetate (18-OH-DOCA) in oil daily, and a group of kidney-intact animals on a normal salt intake was given 2 mg/day. The hormone was not found to increase saline consumption, increase urinary potassium or kallikrein excretion, or depress serum renin activity or potassium concentration. Slight hypertension did develop at 3 weeks in salt-loaded rats on the lowest dose, but this was neither increased by higher dosage or longer treatment, nor reflected by increased heart or kidney weight. The effect of 40-mg pellet implantation of DOCA and 18-OH-DOCA was then compared in unilaterally nephrectomized, salt-loaded, female Fischer 344 rats. The former caused increased saline consumption, hypertension, hypokalemia, and heart and kidney enlargement, whereas 18-OH-DOCA did not. Thus, the hypertensogenic potency of 18-OH-DOCA is, at best, a reflection of its known, very weak, mineralocorticoid activity.

Urinary tetrahydroaldosterone and aldosterone-18-glucuronide excretion in white and black normal subjects and hypertensive patients.

Urinary aldosterone excretion is commonly determined by assay of aldosterone liberated from the acid-labile metabolite, aldosterone-18-glucuronide (Aldo-18-G), which reflects 5-15% of aldosterone secretion. However, since 3alpha, 5beta-tetrahydroaldosterone (TH-Aldo), the major metabolite, reflects 15-40% of aldosterone excretion, determination of its excretion should usually provide a more accurate index of aldosterone secretion. We have validated a RIA for urinary TH-Aldo and compared its excretion in black and white normal subjects and patients with essential hypertension and primary aldosteronism during consumption of low, normal, and high sodium diets. Urinary TH-Aldo excretion averaged 4.5 +/- 2.0 (mean +/- SD) times that of Aldo-18-G. The ratio of excretion of the two remained relatively constant during low, normal, and high sodium diets. There was no difference in the excretion of TH-Aldo or Aldo-18-G in black vs. white normal subjects or hypertensive patients and no age-related changes in the excretion of either metabolite from 20-60 yr of age. Two of nine patients with primary aldosteronism had normal Also-18-G excretion but elevated TH-Aldo excretion. We conclude that determination of both metabolites increases the diagnostic accuracy for primary aldosteronism.

Urinary free 19-nor-deoxycorticosterone and deoxycorticosterone in human hypertension.

The urinary excretion of deoxycorticosterone (DOC) and 19-nor-deoxycorticosterone (19-nor-DOC) was measured using a technique which consisted of the purification of both steroids by high pressure liquid chromatography followed by RIA using specific antibodies. The urinary excretion of DOC was 29.4 +/- 25 ng/24 h (mean +/- SD) in 35 normal subjects, 26 +/- 21 ng/24 h in 46 patients with low renin hypertension (LRHT), and 32 +/- 23 ng/24 h in 16 patients with normal renin hypertension (NRHT). The urinary excretion of 19-nor-DOC was 287 +/- 178 ng/24 h in normal subjects, 224 +/- 167 ng/24 h in LRHT patients, and 235 +/- 170 ng/24 h in NRHT patients. There were no hypertensive patients with increased excretion of 19-nor-DOC. The excretion of 19-nor-DOC increased after 3 days of sodium depletion in normal and hypertensive subjects, but the increment was significantly higher in normotensive subjects. There was no correlation between the excretion of 19-nor-DOC and that of DOC or urinary aldosterone. This study suggests that DOC or 19-nor-DOC does not play a role in the pathogenesis of either LRHT or NRHT and disagrees with previous reports suggesting such a role.

Systemic and regional hemodynamic effects of calcitonin gene-related peptide.

Calcitonin gene-related peptide, a 37-amino-acid neuropeptide, has been shown to be widely distributed in periadventitial nerves throughout the cardiovascular system, particularly in association with coronary arteries. In vivo and in vitro studies have demonstrated that calcitonin gene-related peptide possesses potent vasodilator properties. Circulating calcitonin gene-related peptide is derived primarily from periadventitial nerves, though its systemic and regional hemodynamic effects are unknown. In this study, systemic and regional hemodynamics were determined by the radioactive microsphere technique prior to and following the intravenous administration of 65-pmol and 2.2-nmol doses of calcitonin gene-related peptide and vehicle to three groups of conscious, unrestrained rats. Vehicle administration did not change any systemic or regional organ hemodynamic parameter determined. In contrast, 65 pmol and 2.2 nmol of calcitonin gene-related peptide significantly decreased mean blood pressure and total peripheral resistance and increased heart rate in a dose-dependent manner, while only slightly increasing cardiac output. Both 65-pmol and 2.2-nmol doses of calcitonin gene-related peptide significantly increased blood flow (percentage of cardiac output) to the heart. There was no difference in blood flow to the heart between the two doses. In addition, the 2.2-nmol dose of calcitonin gene-related peptide significantly increased blood flow to the stomach, liver, and skin and decreased it to the brain, kidneys, and spleen. In conclusion, calcitonin gene-related peptide infusion decreases blood pressure in a dose-dependent manner primarily by peripheral vasodilation. In addition, calcitonin gene-related peptide selectively changes regional organ blood flow, particularly to cause coronary vasodilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Systemic and regional hemodynamic effects of dietary calcium supplementation in mineralocorticoid hypertension.

This study was undertaken to determine the systemic and regional hemodynamic effects of long-term dietary calcium supplementation in mineralocorticoid (DOC)-salt hypertension. Systemic and regional hemodynamic measurements were determined by the radioactive microsphere technique in conscious and unrestrained rats (kidneys intact) with DOC-salt-induced hypertension that were pair-fed either a normal calcium (0.6% by weight, n = 12) or a calcium-supplemented (high-calcium) diet (2.5% by weight, n = 12). After 7 to 8 weeks, there were no differences in weight, heart rate, or cardiac output between the two groups. In contrast, the high-calcium rats had a significantly lower mean blood pressure (125 +/- 4 mm Hg, mean +/- SEM) than the normal calcium rats (143 +/- 5 mm Hg); this finding appeared to result predominantly from a reduction in total peripheral resistance. The high-calcium rats had a higher renal blood flow (7.8 +/- 0.5% vs. 6.2 +/- 0.4% cardiac output; p less than 0.05) and lower renal (14.3 +/- 1 vs. 19.3 +/- 2 mm Hg/min/ml/g tissue; p less than 0.05) and jejunal vascular resistance than did the normal calcium rats. Two additional identical groups of normal calcium-and high-calcium-DOC-salt rats (n = 12 each) were also studied. In these rats, serum-ionized calcium decreased significantly (p less than 0.05) from baseline in both groups. Urinary sodium increased in both groups but did not differ significantly. In conclusion, dietary calcium supplementation attenuates the rise in peripheral vascular resistance that accompanies DOC-salt hypertension. This attenuated resistance appears to be relatively selective and is noted particularly in the renal vasculature.

Further evaluation of saline infusion for the diagnosis of primary aldosteronism.

Normal subjects, normal-renin hypertensive patients, and low-renin hypertensive patients were evaluated by intravenous saline infusion and with a fludrocortisone acetate (Florinef) protocol to clarify diagnostic criteria for primary aldosteronism that are recommended for the saline infusion protocol. The patients consumed a 200 mEq sodium, 70 mEq potassium diet for 6 days, and on the last 3 days received Florinef 0.5 mg orally twice daily. On Days 3 and 6, urinary aldosterone and tetrahydroaldosterone excretions were determined, and on Days 4 and 7 plasma aldosterone (PA) was determined at 0600 after overnight recumbency and at 0800 after 2 hours of walking. Although the level of normal PA suppression by saline infusion has been commonly defined as 10 ng/dl, a value of 5 ng/dl was originally recommended. In 20 normal subjects and 45 normal-renin hypertensive patients, we found that the PA was almost always suppressed below 5 ng/dl. In 18 of 75 low-renin patients including five with aldosterone-producing adenoma (APA), the PA was never suppressed below 10 ng/dl; thus, these 18 patients had classical primary aldosteronism by generally accepted criteria. The Florinef protocol was performed in eight of these 18 patients and was abnormal in all. An abnormal Florinef protocol was also found in seven of 15 patients studied with PA suppression after saline infusion to between 5 and 10 ng/dl, but in only one of 24 patients studied with PA suppression below 5 ng/dl. Additional studies in the subgroup with abnormal results from the Florinef protocol indicated that none of these patients had evidence of APA, so they had nontumorous primary aldosteronism (NTPA).(ABSTRACT TRUNCATED AT 250 WORDS)

Synergistic effect of captopril with hydrochlorothiazide for the treatment of low-renin hypertensive black patients.

Diuretics have been particularly successful for treatment of low-renin hypertension (LRH), although they may cause metabolic complications such as hypokalemia and hyperglycemia. Since the efficacy of diuretics is largely limited by reactive angiotensin II production, a combination of a converting enzyme inhibitor with a diuretic should be synergistic, particularly in LRH, where heightened aldosterone production in response to angiotensin II has been noted. Eighteen patients with LRH were treated initially with either captopril alone (450 mg/day) or hydrochlorothiazide (HCTZ) (up to 100 mg/day). Captopril alone only reduced average placebo standing blood pressure from 151/100 to 146/96 mm Hg. Combination of HCTZ with captopril reduced average standing blood pressure to 111/76 mm Hg at 3 months and 116/81 mm Hg at 1 year while allowing reductions in average captopril dosage to 100 mg/day and HCTZ dosage to 40 mg/day and reductions in supplemental potassium administration and in HCTZ-induced hyperglycemia. Captopril monotherapy did not increase urinary excretion of kallikrein, prostaglandin E2, or 6-keto prostaglandin F1 alpha, a metabolite of prostacyclin, and did not reduce urinary aldosterone excretion chronically. Thus, a synergism of captopril with HCTZ may be advantageous in certain patients with LRH.

Plasma aldosterone response to ACTH in primary aldosteronism and in patients with low renin hypertension.

ACTH alpha 1-24 was infused at incremental rates of 12.5-200 mIU/30 min in dexamethasone-suppressed hypertensive patients on a regular sodium diet. The plasma aldosterone response to this stimulus in 8 patients with hyperaldosteronism due to an adrenal aldenoma and 11 with adrenal hyperplasia was significantly greater at all infusion rates (P less than 0.05) when compared with the response in 6 normal subjects on a similar diet. This responsiveness to ACTH in the patients with primary hyperaldosteronism was similar to that of the normal subjects on a low sodium diet. Twelve patients with low renin and 6 patients with normal renin essential hypertension were similarly studied. There was no significant difference in the median aldosterone response between these 2 groups and the normal subjects on a normal diet, but the response was significantly lower compared with that in patients with primary hyperaldosteronism. These data show that patients with hyperaldosteronism from an adrenal adenoma or hyperplasia have a consistent and exaggerated response to ACTH. The hyper-responsiveness is not apparently shared by the majority of patients with low renin essential hypertension and does not support the concept that this group is an intermediate form of primary aldosteronism. Individual patients within this group, however, may have such a response and might be identified by this type of testing.

Urinary 18-hydroxycortisol and its relationship to the excretion of other adrenal steroids.

The urinary excretion of 18-hydroxycortisol was recently reported to be increased in patients with primary aldosteronism who have an adrenal adenoma and in those with glucocorticoid-suppressible aldosteronism. A direct RIA for 18-hydroxycortisol in urine and plasma has been described, and we here report our experience using a similar direct RIA and a more elaborate RIA which includes a preliminary high pressure liquid chromatography (HPLC) purification step. The urinary excretion of 18-hydroxycortisol was compared with that of other adrencorticoids. The urinary excretion of 18-hydroxycortisol in 37 normal subjects using the direct RIA was 112 +/- 49 (+/- SD) microgram/24 h, and that with the HPLC-RIA method was 63 +/- 36 micrograms/24 h. The accuracy and specificity of the HPLC-RIA assay method were confirmed by measuring the steroid after the HPLC step as the glycolic acid ester derivative. The urinary excretion of 18-hydroxycortisol correlated with that of cortisol (r = 0.36; P less than 0.01), 18-oxocortisol (r = 0.42; P less than 0.01), and 19-nordeoxycortisosterone (r = 0.71; P less than 0.001), but did not correlate with the excretion of aldosterone 18-oxoglucuronide (r = 0.25; P = 0.15942). Dexamethasone administration to five normal subjects significantly decreased 18-hydroxycortisol excretion from 81 +/- 47 to 23 +/- 8 micrograms/24 h. ACTH infusion in these subjects receiving dexamethasone significantly raised 18-hydroxycortisol excretion to 147 +/- 37 micrograms/24 h. Five days of a sodium-restricted diet (10 mmoles/day) resulted in a significant (P less than 0.02) increase in 18-hydroxycortisol excretion, but two of eight subjects had decreased excretion, although urinary aldosterone excretion increased, as expected. These studies demonstrate that the direct RIA significantly overestimates urinary 18-hydroxycortisol excretion. These studies also demonstrate that the major factor resulting 18-hydroxycortisol excretion is ACTH. However, since 18-hydroxycortisol excretion may increase during sodium depletion, angiotensin or other factors may also regulate its secretion.