Renal sodium and potassium excretion in sheep given amiloride

When amiloride was given (IV) to unanesthetized ewes, potassium excretion decreased to one-third of baseline values, and sodium excretion increased 6- to 180-fold. Potassium excretion during amiloride administration was relatively invariant with respect to duration (0 to 270 minutes) or rate of amiloride administration (0.125 to 2.0 mg/minute), but sodium excretion clearly increased with both duration and dose rate in individual experiments. This increase was independent of the rate of concomitant saline administration. Thus, sheep fed a normal ration (about 600 mEq of potassium per day) respond to amiloride as do man, dogs, and rats. The relationship of sodium excretion to rate and duration of amiloride administration is not unique to sheep, but has not been stressed in previous studies on other species.