J. S. K. Fan

The effect of corticotrophin (ACTH) administration on the pressor action of angiotensin II, noradrenaline and tyramine in sheep.

1. Pressor responses to angiotensin II, noradrenaline and tyramine were examined in sheep prior to and during the development of corticotrophin‐induced hypertension.

Inter-relationships between Sodium and Potassium Intake and the Blood Pressure Effects of ACTH in Sheep

These studies examine the effect of sodium (Na) and potassium (K) intake on the pressor and metabolic actions of ACTH (20 μg/kg/day) in sheep. After 21 days on each of five regimens in which Na and K intake varied from 0 to 100 mmol/day, no simple relationship between Na and K intake and blood pressure was found. After five days of ACTH treatment, mean arterial pressure (MAP) rose + 5 mmHg in sheep on 0 mmol Na, 0 mmol K (expressed as 0 Na 0 K); + 13 mmHg on 10 Na 700 K; + 5 mmHg on 0 Na 700 K; + 20 mmHg on 700 Na 0 K and + 24 mmHg on 700 Na 700 K. Plasma [K] was unchanged by ACTH on 0 Na 0 K but fell in sheep on the other electrolyte regimens. Water intake increased with ACTH on all regimens except 700 Na 0 K. Blood aldosterone concentration was high in sheep maintained on 0 Na regimens but lower after five days of ACTH treatment in all groups. Blood cortisol and corticosterone concentrations increased with ACTH on all regimens studied.

THE EFFECT OF ADRENAL DENERVATION ON ACTH‐INDUCED HYPERTENSION IN SHEEP

SUMMARY 1. The effect of surgical denervation of the adrenal gland on ACTH‐induced hypertension in the sheep has been examined. ACTH (80 iu/day) was administered for 5 days to eight sheep before and after bilateral surgical denervation of the adrenal.

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. On days 3 and 6, diuretic and natriuretic responses were both significantly increased. Steroid-induced sodium retention may have abolished the natriuretic effect on day 1.

Effect of ACTH and Adrenal Corticosteroids on Renal Function in Sheep

The effects of administration of ACTH and the major ovine adrenal steroids on renal function in conscious sheep were examined. Glomerular filtration rate and effective renal plasma flow increased with

BLOOD PRESSURE AND METABOLIC EFFECTS OF ACTH IN ANEPHRIC SHEEP

1. ACTH (80–100 iu/day) was administered to seven sheep for 3–5 days following bilateral nephrectomy.

EFFECT OF POSTASSIUM, ANGIOTENSIN II AND ACTH ON BLOOD ALDOSTERONE AND CORTISOL IN SHEEP ON DIFFERENT DIETARY POTASSIUM AND SODIUM INTAKES

1. The short term aldosterone response to manipulations of potassium (K), angiotensin II (AII) and ACTH were examined in sheep on a variety of chronic electrolyte regimes.

EFFECT OF ADRENOCORTICAL STEROIDS AND THEIR STRUCTURAL ANALOGUES ON BLOOD PRESSURE IN SHEEP

1. A model of adrenocortical steroid‐induced hypertension based on the effects of ACTH administration has been developed in sheep. The present studies examine the effects of a number of different steroid hormones on blood pressure to investigate their structure‐activity relationships.