Exaggerated natriuresis in ACTH hypertension in sheep.

Adrenocorticotrophic hormone (ACTH) administration to sheep (100 IU/day) produces a sustained increase in arterial pressure within 24 h. The effect of ACTH on excretion of an intravenous saline load was tested in 8 adult cross-bred Merino ewes. A significant diuretic response to saline loading was found after 24 h but no increased natriuresis.

Plasma renin activity and blood corticosteroids in the Australian lungfish Neoceratodus forsteri.

Plasma renin activity (PRA) and blood aldosterone and deoxycorticosterone levels were measured in Australian lungfish. Plasma renin activity was depressed after intravenous infusions of iso-osmotic (0-6%) NaCl but not after hypo-osmotic (0-3%) infusions. The presence of PRA in this fish is consistent with prior reports of renal renin activity in other sarcopterygian fishes.

Measurement of extracellular fluid volume and blood volume in sheep.

Methods are described for the simultaneous measurement of extracellular fluid volume (ECFV) and plasma volume (PV) in sheep using dilution of 82Br (as sodium bromide) and 131I-labelled ovine gamma globulin. Following injection of 82Br (100 micronCi), equilibrium in blood was reached after 3 h at which time only 4% of the injected dose was in rumen water. The ECFV was measured as the mean of the 2- and 3-h bromide space after correction for the relative water content of plasma, the Gibbs-Donnan factor and the loss of 82Br into red blood cells.

Adenosine 3'5' cyclic monophosphate metabolism in patients with severe depressive illness.

The daily excretion of adenosine 3'5' cyclic monophosphate (c-AMP) in a group of 19 patients with a severe depressive illness was found to be significantly decreased when compared with that from a group of euthymic patients being treated for other disorders in the same ward. The daily excretion of the depressed patients increased during the period of treatment and recovery from the illness. Treatment with a tricyclic antidepressant caused a greater increase than electroconvulsive treatment (ECT).

Angiotensin II analogues and aldosterone secretion in sodium-deficient sheep.

1. The angiotensin analogues Sar1-Ala8-angiotensin II (AII), Sar1-Ile8-AII, Sar1-Leu8-AII, Sar1-Thr8-AII, [Des1-Asp]-Ile8-AII and [Des1-Asp]-Sar2-Ile8-AII and converting enzyme inhibitor (SQ 80221) infused by intra-adrenal arterial infusion had no effect on aldosterone secretion in sodium-deficient sheep at doses in excess of those shown to block exogenous angiotensin II or III infusion. 2.

Further unravelling of the causes of ACTH-induced hypertension in the sheep.

1. Acute severe sodium subtraction (20-25% of total exchangeable sodium) before or during treatment with adrenocorticotrophic hormone (ACTH) does little to modify the increase in blood pressure induced by ACTH. 2.

Mineralocorticoid receptors in sheep kidney and parotid: studies in Na+ replete and Na+ deplete states.

1. As an adrenalectomized sheep becomes progressively more Na+ deplete, its salivary electrolyte secretion becomes increasingly sensitive to exogenous aldosterone administration. 2.

Concerning the independence of the basis of hypertension due to ACTH or renovascular constriction.

Administration of ACTH to four sheep with chronic renovascular hypertension resulted in an increase in blood pressure which was at least as high as that described in normotensive sheep and could be completely accounted for by an increase in cardiac output.

Increased water drinking induced by sodium depletion in sheep.

Forty-eight hours of sodium depletion by acute cannulation of a parotid duct, via the buccal papilla, in the sheep, resulted in a progressive decrease in salivary secretion rate, salivary, urinary and plasma [Na] and no change in plasma [K]. In the first 24 h of Na depletion water intake was significantly increased. As normal sheep parotid saliva [Na] is higher than plasma [Na] and salivary loss over the first 24 h represented Na loss in excess of water relative to extracellular proportions, increased water intake was not osmotically induced.

The effect of pregnancy on mineralo- and gluco-corticoid secretion in the sheep.

1. The peripheral blood concentrations of aldosterone, corticosterone and cortisol were measured during pregnancy in conscious, undisturbed sheep. 2.

Rapid radioisotopic procedure for determination of nortriptyline in plasma.

With the widespread use of tricyclic antidepressant drugs, the relationship between the concentration of the drug in the plasma and the therapeutic response is of considerable interest. We describe a double-isotope derivative dilution procedure for measuring plasma nortriptyline. In the method, [14C]nortriptyline is used for estimating procedural losses and [3H]acetic anhydride for derivative formation.

Blood corticosteroids in Australian marsupial and placental mammals and one monotreme.

Peripheral blood corticosteroid levels were determined in nine species of Australian marsupial (Eastern grey kangaroo, black-tailed, Bennett's and pademelon wallabies, quokka, wombat, koala and Western native and tiger cats), one species of monotreme (echidna) and one placental Australian mammal (dingo). Animals were obtained or bled with minimal disturbance and came from areas considered to have adequate sodium content of the vegetation. Aldosterone, corticosterone, cortisol, 11-deoxycorticosterone and 11-deoxycortisol were measured and levels found to be similar to five introduced eutherian species (sheep, cow, dog, fox and man) with the exception of the koala and the wombat.

The measurement of plasma levels of tricyclic antidepressant drugs.

A double-isotope derivative dilution procedure for measuring plasma levels of Nortriptyline is described. The assay is specific, sensitive, precise and reproducible. Studies on the variation in steady-state plasma levels are described on a fixed oral dosage of nortriptyline.

Regulation of aldosterone in the guinea-pig--effect of oestrus cycle, pregnancy and sodium status.

The blood concentrations of aldosterone, corticosterone and cortisol were measured in conscious, non-stressed guinea-pigs using a double isotope dilution derivative assay procedure. Aldosterone levels in the guinea-pig were high when compared with those of other species. The concentration of aldosterone, 37-7 +/- 15-9 ng/100 ml (x +/- SD), and cortisol, 31-8 +/- 10-1 mug/100 ml, found in non-pregnant females on a moderate sodium intake was significantly greater than in males (aldosterone 22-2 +/- 2-4 ng/100 ml and cortisol 19-3 +/- 5-7 mug/100 ml).

Effect of adrenal arterial infusion of saralasin (P113) on aldosterone secretion.

To test the role of the renin/angiotensin system in aldosterone regulation, Sar1-Ala8-angiotensin II (P113) was infused into the arterial blood supply of transplanted adrenal glands in conscious sheep. Effects on the aldosterone response to infused angiotensin II and III in sodium replete sheep were compared with effects in sodium deficiency. Adrenal arterial infusion of P113 up to 1,000 mug/h for 1-2h did not consistently alter the high aldosterone secretion rates of sodium-deficient sheep.

Aldosterone secretion during high sodium cerebrospinal fluid perfusion of the brain ventricles.

Conscious sheep with permanent indwelling cannulae in the lateral ventricles and the cisterna magna were Na depleted and then perfused for 9 h with an artificial CSF solution. There were 3 experimental groups: Group I (n=5) received perfusion with aritifical CSF containing NA 170 MEq./1, Group II (n=7) received perfusion with artificial CSF containing Na 145 mEq.

Effect of ouabain on adrenal potassium balance in sheep.

A previous study revealed that ouabain caused a marked decrease in aldosterone secretion, but the adrenal K status was not clear from those data. The present study investigated the magnitude and time course of change in adrenal K balance when ouabain was administered into the adrenal arterial supply of the in situ adrenal of conscious sheep. Ouabain at an adrenal arterial plasma concentration of approximately 2.

Effect of intravenous infusion of corticosteroids on blood pressure, electrolytes, and water metabolism in sheep.

ACTH administration (80 IU/day for 5 days), which produces hypertension and charateristic metabolic effects in sheep (38), has been compared with the effect of intravenous infusion of cortisol (5 mg/h), corticosterone (0.5 mg/h), deoxycorticosterone (50 mug/h), and 11-deoxycortisol (1 mg/h), each given singly for 5 days. Further, a mixture consisting of aldosterone (3 mug/h), cortisol (5 mg/h), deoxycorticosterone (25 mug/h), corticosterone (0.