Regulation of aldosterone biosynthesis during sodium deficiency. Evidence for an essential role of the pituitary gland.

The aldosterone response to adrenocorticotropic hormone (ACTH) and angiotensin II (AII) was evaluated in patients with pituitary insufficiency before and after dietary sodium restriction (10 mEq Na+/day for 12 days). On normal sodium intake, plasma aldosterone concentration and plasma cortisol concentration failed to change from control levels in response to a single injection of ACTH or to a continuous 1-hour infusion of AII in patients with pituitary insufficiency. In response to dietary sodium restriction for 12 days, plasma renin activity (PRA) increased fivefold in patients with pituitary insufficiency, while plasma aldosterone concentration failed to increase significantly, averaging 11.0 +/- 3.1 before and 12.3 +/- 3.7 ng/dl (ns, p greater than 0.05) after sodium deficiency. Although aldosterone secretion failed to increase during sodium deficiency, the patients came into balance at 10 mEq without a significant change in arterial blood pressure (BP). In sharp contrast to the lack of aldosterone response to ACTH before sodium deficiency, plasma aldosterone concentration increased markedly from 12.9 +/- 3.3 to 156 +/- 17.3 ng/dl (p less than 0.001) in response to ACTH after sodium deficiency. Although the adrenal glomerulosa cells were markedly sensitive to ACTH during sodium deficiency, they remained almost totally refractory to AII since aldosterone secretion failed to increase significantly in response to continuous infusion of a pressor dose of AII for 1 hour. Replacement therapy with ACTH gel for 3 months in patients with pituitary insufficiency failed to restore a normal aldosterone response to either ACTH or AII. These data demonstrate that some non-ACTH pituitary factor(s) is essential for a normal aldosterone response to ACTH, AII, and sodium deficiency.

The eye and visual nervous system: anatomy, physiology and toxicology.

The eyes are at risk to environmental injury by direct exposure to airborne pollutants, to splash injury from chemicals and to exposure via the circulatory system to numerous drugs and bloodborne toxins. In addition, drugs or toxins can destroy vision by damaging the visual nervous system. This review describes the anatomy and physiology of the eye and visual nervous system and includes a discussion of some of the more common toxins affecting vision in man.

Extensive detachment of Descemet membrane after holmium laser sclerostomy.

PURPOSE: To describe a corneal complication and its surgical repair after holmium laser sclerostomy. METHOD: A 63-year-old woman had extensive detachment of Descemet membrane 3 months after holmium laser sclerostomy. The authors describe the case history of a detached Descemet membrane secondary to holmium laser sclerostomy and its subsequent repair. RESULTS: The patient achieved a visual acuity of 20/20 in the involved eye after descemetopexy with sodium hyaluronate and air combined with suturing. CONCLUSIONS: Detachment of the Descemet membrane should be recognized as a potential complication of holmium laser sclerostomy. Suturing should be considered as a method of repair if there is not spontaneous reattachment of the Descemet membrane.

Role of angiotensin II and potassium in the long-term regulation of aldosterone secretion in intact conscious dogs.

The aldosterone response to long-term infusion of angiotensin II and potassium was studied in intact conscious dogs. Plasma aldosterone concentration (PAC), plasma renin activity (PRA), and plasma cortisol concentration (PCC) were determined by radioimmunoassay. In ten dogs maintained on angiotension II infusion (5 ng/kg min-1) for 14 days, PAC increased from 6.9 plus or minus 2.9 to 18.6 plus or minus 4.7 ng/100 ml plasma (mean plus or minus SE) within ten minutes after beginning the infusion, reached a maximum level of 28.3 plus or minus 6.8 ng/100 ml plasma by one hour, and returned to control levels by six hours. PCC increased from 0.6 plus or minus 0.2 to 3.9 plus or minus 1.0 mu-g/ 100 ml plasma within one hour after angiotensin II infusion and returned to control levels by six hours. During the next 14 days of angiotensin infusion, PAC remained at control levels, PRA was undetectable by radioimmunoassay, and mean arterial blood pressure was elevated 29 plus or minus 4 mm Hg above control levels. In ten dogs maintained on KCL infusion (250 mEg/day) for 15 days, PAC increased from 6.8 plus or minus 2.4 to 13.6 plus or minus 3.4 ng/100 ml plasma within 24 hours, averaged 22.4 plus or minus 4.3 ng/100 ml plasma by 48 hours, and remained elevated for the next 12 days, averaging 21.8 plus or minus 5.6 ng/100 ml plasma. During the next 14 days of KCL infusion, serum Kn increased from 4.1 plus or minus 0.3 to 4.9 plus or minus 0.5 ME1/L, and PRA decreased from 1.25 plus or minus 0.3 to 0.65 plus or minus 0.2 ng/ml/hr. PCC averaged 0.73 plus or minus 0.4 mu-g/100 ml plasma in the control samples and failed to change significantly during KCL infusion. These data indicate that chronic angiotensin II infusion into intact conscious dogs at rates capable of maintaining elevated arterial blood pressure results in a transient increase in aldosterone secretion that lasts only a few hours, while chronic infusion of potassium ions at rates that produce a minor increase in serum Kn results in a sustained increase in aldosterone secretion.

Response of arterial blood pressure, plasma renin activity and plasma aldosterone concentration to long-term administration of captopril in patients with severe, treatment-resistant malignant hypertension.

1. The response of arterial blood pressure, plasma renin activity and plasma aldosterone concentration to inhibition of angiotensin I converting enzyme (kininase II) with captopril has been studied in patients with severe, treatment-resistant, malignant hypertension. 2. Nine patients with a past history of severe hypertension, supine diastolic blood pressure greater than 120 mmHg before conventional antihypertensive therapy and resistant to conventional antihypertensive therapy were studied. 3. Captopril administration resulted in a marked decrease in arterial blood pressure and plasma aldosterone concentration and an increase in plasma renin activity. 4. Although arterial blood pressure remained significantly below the values observed during the control period, pressure did tend to increase again after 3 days. Addition of hydrochlorothiazide kept arterial pressure significantly below pretreatment control values.