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 micrograms/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 100 K; + 5 mmHg on 0 Na 100 K; + 20 mmHg on 100 Na 0 K and + 24 mmHg on 100 Na 100 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 100 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.