The Effect of Potassium on the Hypertensive and Electrolyte Responses to Acth Administration in Sheep

Abstract

This study examines the blood pressure and electrolyte response to adrenocorticotrophic hormone (ACTH) in K loaded sheep to test the hypothesis that ACTH-induced hypertension is blunted in K loaded sheep.

ACTH treatment in sheep on a ‘normal’ Na (70–100 mmol/day) and high K intake (≃800 mmol/day) increased mean arterial pressure (MAP) by upto 17 mmHg over 5 days. Cardiac rate and urinary Na excretion also increased. Plasma [Na] and [K] fell with ACTH. On a lower Na (30 mmol/day) and high K intake (≃800 mmol/day) ACTH raised MAP by upto 16 mmHg over 5 days. Cardiac rate, urinary Na and K excretion also increased. Plasma [Na] fell and plasma [K] was unchanged. Thus, ACTH hypertension is not modified in chronically K loaded sheep, although electrolyte responses are different from normal.

Key Words:

• Potassium
• ACTH
• Sheep
• Blood pressure
• Electrolytes