Differing effects of metoclopramide and adrenocorticotropin on plasma aldosterone levels in glucocorticoid-suppressible hyperaldosteronism and other forms of hyperaldosteronism

To investigate possible dopaminergic effects on aldosterone production, we administered the dopamine antagonist metoclopramide to 11 normal subjects, 8 patients with primary aldosteronism due to adenoma or hyperplasia, and 5 other patients with the glucocorticoid-suppressible form of hyperaldosteronism (GSH). All subjects except for those with GSH responded to metoclopramide with an increase in plasma aldosterone concentration even when endogenous ACTH was suppressed by dexamethasone pretreatment. This increase occurred without apparent mediation of other recognized stimuli for aldosterone secretion. In contrast, the patients with GSH failed to show any aldosterone response while receiving dexamethasone, but demonstrated a rise in plasma aldosterone concentration when dexamethasone was withheld. The responses in the patients with both forms of primary aldosteronism were greater in magnitude than in the normal subjects or in the subjects with GSH when not receiving dexamethasone. These studies, while demonstrating differences between the subtypes of hyperaldosteronism in their responsiveness to metoclopramide, indicate that ACTH or some other factor may exert a permissive effect in GSH for the aldosterone response to metoclopramide. A graded infusion of ACTH revealed a greater aldosterone response in GSH compared to that in the other groups, further suggesting the importance of ACTH in this disorder.

Estimation of domain length of chicken erythrocyte chromatin

Chromatin of chicken erythrocyte nuclei was extracted by digestion with micrococcal nuclease. The length distribution of the soluble chromatin was determined by gel electrophoresis and electron microscopy. These results were fitted with a theoretical distribution which was an outcome of the domain model proposed by Igo-Kemenes and Zachau (Igo-Kemenes, T. and H.G. Zachau (1977) Cold Spring Harbour Symp. Quant. Biol. 42, 109-118). A domain length of 45 kbp was obtained.

Cardiovascular, humoral, and renal effects of phenoxybenzamine in hypertension

We examined the effects of alpha adrenergic receptor blockade with phenoxybenzamine on various parameters related to blood pressure regulation in 10 normotensive and 12 essential hypertensive subjects. The responses were observed before and after phenoxybenzamine treatment during standardized maneuvers of volume expansion with saline infusion and volume contraction with a diuretic. Alpha adrenergic blockade produced a significantly greater (P less than 0.02) reduction in blood pressure in the hypertensive group than in the normotensive subjects. The baroreceptor response, evaluated by comparing the change in plasma norepinephrine concentration in relation to the change in blood pressure, was significantly reduced (P less than 0.05) in hypertensives compared to normal subjects. Plasma and urinary norepinephrine concentration, which were similar in the two groups, increased in both during phenoxybenzamine treatment. There was no significant change in the mean levels of plasma renin activity or plasma aldosterone concentration in either group after phenoxybenzamine treatment. However, the relationship between plasma renin activity and plasma aldosterone levels, as judged by linear regression analysis, was significantly altered (P less than 0.05) by phenoxybenzamine therapy in both groups. The latter may reflect an effect of phenoxybenzamine on the metabolism or secretion of aldosterone. These results, utilizing an alpha adrenergic antagonist, confirm the enhanced vascular reactivity and diminished baroreceptor function in essential hypertension; no evidence for an alpha adrenergic effect on plasma renin activity could be demonstrated in normotensive or hypertensive subjects.

Electroacupuncture and its effect on rat hepatic functions

The effect of single, acute (7 pulses/sec., 0.75 volt) and chronic (4 pulses/sec., 0.75 volt) electroacupuncture (EA) treatment on alternate days for a period of 21 days on hepatic functions of rats were studied at cellular and subcellular levels. The points used for EA were Shenshu, Dachangshu and Zusanli. After chronic treatment, (a) protein, RNA, phospholipid, and cholesterol contents of whole liver and liver microsomal fraction increased significantly, (b) liver microsomal G-6-Pase activity increased significantly, (c) microsomal lipid peroxidation value decreased, (d) lipase activity increased. After acute treatment, (e) phospholipid, and cholesterol contents of the whole liver and liver microsomal fraction increased significantly, (f) liver microsomal G-6-Pase activity increased significantly, (g) liver microsomal lipid peroxidation value decreased, (h) GPT and lipase activity of liver increased. The parameters unchanged in acute treatment were as follows: (i) protein, RNA content, (j) GOT activity of the liver, (k) SGOT and SGPT activity, (1) hepatic triglyceride. The parameters unchanged in chronic treatment were as follows: (m) GOT and GPT activity of the liver, (n) SGOT and SGPT activity, (o) hepatic triglyceride. No apparent harmful effect of EA on rat hepatic functions is obvious from present study.

The renin-angiotensin-aldosterone system in Cushing's syndrome and pheochromocytoma

We investigated the status of the renin-angiotensin-aldosterone axis in 5 patients with Cushing's syndrome and 7 patients with pheochromocytoma. In most of the patients with Cushing's syndrome no significant abnormalities of the renin-angiotensin-aldosterone system could be detected. In 4 out of 7 patients with pheochromocytoma, plasma renin activity remained high after saline suppression and decreased into the normal range in all 4 patients after removal of pheochromocytoma. These results imply that the postulated mineralocorticoid excess was not present in the patients with Cushing's syndrome studied. In pheochromocytoma, high levels of plasma catecholamines contribute to a high renin state which may have pathophysiologic implications.

Unilateral hypersecretion of aldosterone associated with adrenal hyperplasia as a cause of primary aldosteronism

In 3 patients with longstanding hypertension and spontaneous or diuretic-induced hypokalemia, the diagnosis of primary aldosteronism was established by the dual criteria of non-suppressible plasma aldosterone level and suppressed plasma renin activity. Preoperative studies of the etiology for the hyperaldosteronism using the postural plasma aldosterone test and adrenal venous steroid measurements gave conflicting results. On the basis of the differential adrenal venous steroid content, which suggested an unilateral adrenal source for the aldosterone hypersecretion, presumed to be adrenal adenoma, each patient was operated upon. In each case the excised adrenal revealed adenomatous or macronodular hyperplasia. Reinvestigation of the patients 3 to 12 months after the adrenalectomy showed that the dynamics of the renin-aldosterone axis was now restored to the normal state even though the patients remained hypertensive. These findings indicate that unilateral hypersecretion of aldosterone associated with adrenal hyperplasia can occur in some patients with primary aldosteronism simulating that due to an aldosteronoma. Such observations also raise questions about the pathogenesis of the adrenal hyperplasia and seem to add further complexity to the evaluation of patients with hyperaldosteronism.

The renin-angiotensin-aldosterone system and hypertension in primary hyperparathyroidism

To evaluate the role of the renin-angiotensin-aldosterone system in the hypertension associated with primary hyperparathyroidism, we measured plasma renin activity and aldosterone concentration before and after maneuvers to suppress and stimulate this system in 11 hypertensive patients with primary hyperparathyroidism. We also measured plasma or urinary norepinephrine concentration to examine the role of catecholamines in the hypertension. The results were compared with an age- and race-matched control population. While the mean plasma aldosterone concentrations were normal, the mean plasma renin activity in response to furosemide stimulation was subnormal in subjects with hyperparathyroidism. Plasma or urinary norepinephrine concentrations were within the normal range. Thus a specific abnormality of the renin-angiotensin-aldosterone system or catecholamines could not be identified in these hypertensives with primary hyperparathyroidism.

Primary aldosteronism: effects of inhibition of ACTH and potassium administration on plasma aldosterone concentration

The relative roles of ACTH, angiotensin and potassium in influencing aldosterone secretion in primary aldosteronism were assessed by direct or indirect means. In untreated patients with primary aldosteronism caused either by adrenal adenoma or hyperplasia plasma aldosterone and cortisol concentrations fluctuated in unison and dexamethasone reduced both hormones markedly. Only when renin-angiotensin system was greatly activated and plasma potassium normalized by medical treatment was dexamethasone less successful in lowering plasma aldosterone concentration. Potassium infusion of 10,20 and 30 mEq/hr in patients with adenoma failed to elicit any increase in plasma aldosterone concentration despite significant increases in plasma potassium levels. These results suggest that patients with primary aldosteronism due to adrenal adenoma are relatively more sensitive to small changes in plasma ACTH level than those in plasma angiotensin or potassium levels. In recumbent patients with adrenal hyperplasia ACTH also modulates plasma aldosterone concentration.

Restoration of renin-aldosterone dynamics to normal following surgery in primary aldosteronism

Little is known regarding the response of the renin-angiotensin-aldosterone system to dynamic maneuvers after surgical removal of an aldosterone-producing adenoma or whether normal renin-aldosterone relationships are restored following surgery. We utilized maneuvers designed to assess the adequacy of aldosterone suppression and renin stimulation to rapid changes in sodium and fluid volume status to examine these relationships in 21 patients before and after surgery for primary aldosteronism. All patients failed to suppress plasma aldosterone normally after intravenous saline infusion and failed to stimulate renin activity into the normal range following diuretic-induced sodium and volume depletion. No relationship between renin and aldosterone was discerned. The studies were repeated 6 mo. to 4 yrs. after unilateral adrenalectomy in all 21 patients. In every case the normal suppression of aldosterone and stimulation of renin was observed. Moreover a significant (p less than 0.001) relationship between renin and aldosterone was demonstrable. Thus in this population of patients with surgically responsive primary aldosteronism, no abnormality of aldosterone production persisted.

Hyperaldosteronism due to unsuspected adrenal carcinoma: discovery during investigation of hypertension in a young woman

During investigation for hypertension a 19-year-old black woman was found to have an unsuspected adrenal carcinoma. Hyperaldosteronism was established as the cause of the hypertension by observing suppressed plasma renin activity and nonsuppressible plasma aldosterone concentration. The causal relationship was confirmed by a cure of the hypertension and a return in the responsiveness of the renin-angiotensin-aldosterone axis to normal after removal of the carcinoma. This report emphasizes the value of a comprehensive investigation of hypertension, especially in young patients.

Genetic and pathophysiologic studies of a new kindred with glucocorticoid-suppressible hyperaldosteronism manifest in three generations

This report describes investigations in a new kindred with dexamethasone-suppressible hyperaldosteronism affecting three successive generations. The presumptive diagnosis was first made in a 7-yr-old boy and led to the identification of the disorder in his mother and grandmother. Several other members of the family were investigated. Genotyping and HLA typing were also performed. To further explore the nature of this unusual disorder, urine from the three patients documented to have the syndrome was assayed for an aldosterone-stimulating factor recently reported to be found in patients with idiopathic aldosteronism. None of these patients showed measurable activity of such a urinary factor. The identification of members in three generations strongly supports the heritable nature of the disorder and probable autosomal dominant type of transmission. The absence of urinary aldosterone-stimulating factor in these patients further supports the tenet that the disorder is pathogenetically distinct from idiopathic aldosteronism, since both disorders are usually associated with bilateral adrenal hyperplasia.

Triamterene-thiazide combination: alternative therapy for primary aldosteronism

The hypertension and hypokalemia of primary aldosteronism are related to excessive aldosterone secretion. Spironolactone, an aldosterone antagonist, is used in high doses to treat the disorder, but it may induce a number of side effects that can limit its use. We investigated the feasibility of treating a group of eight patients with hyperaldosteronism with a triamterene-thiazide combination to induce volume depletion and increase serum potassium concentration. All patients responded with normalization or near normalization of blood pressure. Serum potassium could be maintained within the normal range with or without potassium supplements in all but one patient. The effectiveness of the therapy suggests that thiazide-triamterene treatment may offer an alternative in some patients with primary aldosteronism who do not tolerate spironolactone.

Stimulation of aldosterone secretion by metoclopramide in humans: apparent independence of renal and pituitary mediation

Metoclopramide (MP), a dopamine antagonist, stimulates secretion of aldosterone by a mechanism which has not been defined. We examined a potential role for either the kidney or the pituitary to mediate MPs effect on aldosterone secretion. Responses to MP administered i.v. were measured in six anephric and six hypopituitary patients as well as in six normal subjects. MP increased the plasma aldosterone concentration (PAC) in normal subjects in a fashion similar to what had previously been reported. MP produced no increase in plasma levels of renin activity (PRA), cortisol, potassium, or sodium. Three of six anephric patients (all of whom had undetectable PRA) responded to MP with increases in PAC; the magnitude of these responses correlated with the plasma potassium concentration. All six hypopituitary patients showed increases in PAC after MP administration. MP increased plasma prolactin levels in normal subjects and anephric patients; one hypopituitary patient had high basal plasma prolactin levels which increased with MP. In conclusion, neither the kidney nor the pituitary is involved in the mechanism for MP stimulated aldosterone production. These observations suggest that MP may act on the adrenal to evoke secretion of aldosterone.

Primary aldosteronism due to unilateral adrenal hyperplasia

A 45-yr-old man with hypertension, hypokalemia, low plasma renin, and hyperaldosteronism was studied. Plasma and urine aldosterone were consistently above normal, remaining abnormally high even on a 300-meq sodium intake. Plasma aldosterone had a marked circadian rhythm, which was correlated with plasma cortisol. Aldosterone secretion was temporarily suppressed after dexamethasone administration and was stimulated by exogenous ACTH. The effect of posture was variable in the eight studies performed, possible due to episodic secretion of aldosterone observed near the sampling times of 0800 and 1200 h. Blood from the right adrenal vein contained 50--100 times more aldosterone than the left adrenal venous samples. The right adrenal gland was excised and found to contain many microscopic subcapsular nests of clear cells. Plasma aldosterone, renin, and potassium returned to normal after surgery, and blood pressure fell to 120/75 over the next 8 months. Three years later, the patient is normotensive without drugs.

Differences between adrenal adenoma causing primary aldosteronism and other adrenal tissues in the incorporation of labeled steroid precursors into their products

The incorporation and conversion of several labeled steroid precursors into their products were examined in slices of adrenal tissue from two patients with primary aldosteronism and compared with that in "normal" adrenal tissue and adrenal tissues from a patient with Cushing's syndrome. The products of the incorporation were separated by Sephadex LH-20 column chromatography. The major products of conversion in the adenomatous tissue of primary aldosteronism were 18-hydroxycorticosterone and lesser amounts of aldosterone. Smaller amounts of 18-hydroxycorticosterone were isolated from all other adrenal tissues studied. No aldosterone could be recovered after incubating any of the adrenal tissue studied with labeled 18-hydroxy-11-deoxycorticosterone or 18-hydroxycorticosterone as precursor steroid. These in vitro results seem to suggest that there is increased 18-hydroxylation in the adenoma of primary aldosteronism compared with other tissues and that relatively more 18-hydroxycorticosterone is produced in such tissue than aldosterone.

Childhood primary aldosteronism due to an adrenal adenoma: preoperative localization by adrenal vein catheterization

Primary aldosteronism resulting from an adrenal adenoma is rare in children. An 8 1/2-year-old girl was found to have hypertension and spontaneous hypokalemia, both detected as incidental findings. Subsequent investigations revealed inappropriately elevated levels of plasma and urinary aldosterone with suppressed plasma renin activity. Adrenal vein blood sampling and venography suggested the presence of left adrenal adenoma which was confirmed at surgical exploration and pathologic examination. All the clinical and biochemical abnormalities were corrected by the adrenalectomy. The differential diagnoses of various types of hyperaldosteronism and/or hypokalemia in such a clinical setting are discussed.

Diagnosis and localization of pheochromocytoma. Detection by measurement of urinary norepinephrine excretion during sleep, plasma norepinephrine concentration and computerized axial tomography (CT-scan)

The feasibility of differentiating patients with pheochromocytoma from other hypertensive patients by measuring urinary excretion rates of norepinephrine during sleep, a period of physiologic suppression of norepinephrine release, was investigated. The mean excretion rates of norepinephrine in 248 normal subjects and in 109 patients with essential hypertension were 1.03 +/- 0.03 and 1.12 +/- 0.06 (SEM) micrograms/hour, respectively, whereas the lowest excretion rate among the six patients with pheochromocytoma was about seven times higher. Plasma norepinephrine concentration in patients with pheochromocytoma was also consistently above the range observed in both normotensive and hypertensive subjects. CT scan correctly identified the same tumors visualized by selective arteriography. It is suggested that the usefulness of these approaches will provide simpler means of screening and detecting pheochromocytoma.

Detection of adrenal tumors by computerized tomographic scan in endocrine hypertension

Localization of adrenal lesions in various adrenal disorders can be difficult. An attempt to identify the adrenal tumors in ten patients with pheochromocytoma, Cushing's syndrome, or primary aldosteronism was made using computerized tomographic (CT) scans. The adrenal tumor was visualized in eight patients. The CT scan appears to be a promising noninvasive technique for localization of adrenal tumors.

Primary aldosteronism: diagnosis, localization, and treatment

New diagnostic techniques have enhanced the detection of primary aldosteronism. However, the response of blood pressure after operation in unilateral and bilateral adrenal disease is different. We have compared four localizing techniques--adrenal venography, adrenal isotopic scanning, a modified adrenal venous sampling for steroid measurements, and the anomalous postural decrease in plasma aldosterone concentration--in 51 patients with primary aldosteronism, all of whom had undergone operative confirmation. Adrenalectomy resulted in normal blood pressure in 59%, improvement in 25%, and no change in 16%. Correct localization of the lesion was obtained in 47% by the adrenal isotopic scan, in 66% by adrenal venography, and in 91% by the modified adrenal venous hormone technique despite four false-positives. Of the 26 patients with an anomalous postural decrease in plasma aldosterone, 88% had a unilateral lesion.

Effect of bedrest on circadian rhythms of plasma renin, aldosterone, and cortisol

Previous studies of normal men after 5 d of bedrest showed that circulatory instability on head-up tilt or standing is preceded by increased plasma renin activity (PRA) at bedrest. In the present study, the circadian rhythms of PRA, aldosterone, and cortisol have been observed in five normal men on a constant diet. In ambulatory controls, PRA and aldosterone increased normally after standing. On the third morning of bedrest, PRA was higher than before, and at noon, PRA was higher than in standing controls. The nocturnal peaks of PRA resulting from episodic renin secretion during sleep were higher after bedrest. Plasma aldosterone was also increased by bedrest. The findings are compatible with the theory that intermittent beta-adrenergic nerve activity during sleep is increased after bedrest, but other factors, such as loss of body sodium and a lower plasma volume, may also be involved.

The effects of temperature and plasma cortisol on distribution of aldosterone between plasma and red blood cells: influence on metabolic clearance rate and on hepatic and renal extraction of aldosterone

Aldosterone enters red blood cells (RBC) to a greater extent at 37 C than at lower temperatures. The ratio of 3H-aldosterone concentration in RBC to that in plasma increases from 0.2 at 4 C to 0.7 at 37 C when cortisol concentration is low. Increasing plasma cortisol increases the RBC/plasma aldosterone ratio. When plasma transcortin (CBG) is saturated with cortisol, the RBC/plasma ratio of 3H-aldosterone approaches 0.93, the ratio observed in RBC incubated in 4% albumin solution. The effects of plasma cortisol and temperature on the RBC/plasma ratio reflect an affinity of aldosterone for plasma CBG greater than the affinity for plasma albumin or RBC. Hepatic extraction averages 92% of plasma and RBC aldosterone. Neither hepatic extraction nor renal extraction (less than or equal to 20%) is significantly altered by changing plasma cortisol concentration. Whole blood MCR of aldosterone is unaffected by redistribution of aldosterone from plasma to RBC when plasma cortisol increases, but both plasma cortisol and the temperature at which blood is separated affect the RBC/plasma ratio of 3H-aldosterone and thus change the calculated plasma MCR. The RBC transport of aldosterone, and its dependence on temperature and plasma cortisol, must be taken into account in the evaluation of plasma aldosterone concentration.

Transient fall and subsequent return of high aldosterone secretion by adrenal adenoma during continued dexamethasone administration

Plasma aldosterone concentration was consistently decreased by 50% or more in 6 patients with aldosterone-producing adenoma on the first day of dexamethasone administration, only to rise subsequently with continued use of dexamethasone while plasma cortisol concentration remained suppressed. The secondary rise in plasma aldosterone was not related to measured changes in known stimuli of aldosterone secretion. It is probable that the observations result from intrinsic alteration of aldosterone synthesis in the adenoma during prolonged ACTH suppression.

Assessment of 11beta-hydroxylase activity with plasma corticosterone, deoxycorticosterone, cortisol, and deoxycortisol: role of ACTH and angiotensin

In this study we evaluated the role of ACTH and angiotensin on regulation of activities of 11beta-hydroxylases of the adrenal cortex. The ratio of the plasma concentrations of 11 deoxycorticosterone (DOC) to plasma corticosterone (B) reflected the activity of the enzyme of the B and/or aldosterone pathways, and the ratio of plasma 11-deoxycortisol (S) to plasma cortisol (F) as the activity of the enzyme in the F pathway. In normal subjects, both ratios were significantly lower at 0800-0900 h (Doc to B, .01+/-.004, mean+/-SE, n=10; and S to F, .01+/-.003) than at 2000 h (DOC to B, .028+/-.024 and S to F, .015+/-.005). The plasma levels of DOC, B, S and F were all significantly lower at 2000-2100 h than at 0800-0900 h. In contrast 9 patients with Cushing's syndrome exhibited no diurnal change in the ratios. The ratios increased substantially following dexamethasone or metyrapone administration. A high or low salt diet and an angiotensin infusion produced no significant effect on the ratios. The plasma concentration of all four steroids was increased by more than 50% by an infusion of angiotensin. Four hours after administration of 80 mg of Lasix at 0800 h to 10 normal subjects, the ratios of DOC to B and S to F increased significantly (P less than .02), an effect possibly related to a decreased secretion of ACTH.

CONCLUSIONS

1) 11beta-hydroxylase activity of the B and/or aldosterone and F pathways appears to change in parallel with ACTH secretion, and 2) although angiotensin stimulates steroidogenesis of the pathways, it has no apparent effect on 11beta-hydroxylase activity.

Cushing's syndrome in a patient with an empty sella turcica and a microadenoma of the adenohypophysis

A patient with Cushing's syndrome and an empty sella turcica is presented. A pituitary microadenoma was removed by the transsphenoidal approach. The Cushing's syndrome was alleviated, and the function of the other pituitary trophic hormones has remained normal eight months after surgery. It is emphasized that an empty sella turcica does not rule out a pituitary tumor. The therapeutic implications are discussed.