Plasma Potassium and Sodium Appetite; The Effect of Potassium Infusion in Sheep

Abstract

SUMMARY Small, but statistically significant, changes of plasma potassium concentration were induced in sheep by 500 ml intravenous infusions of saline with potassium chloride (containing 32, 80 mequiv. K + ) administered over 90 min. The preference for drinking 300 mm solutions of sodium bicarbonate rather than water was tested for 2 h following the start of infusions and did not differ whether the latter were of saline or KCl. Two hours after KCl infusions, plasma potassium had fallen below pre-infusion levels; comparable values occurred 2 h after control infusions of saline alone. Sodium preference differed between morning and afternoon experiments during saline and KCl infusions; such differences in preference were not observed without infusions. The effect of infusions on plasma sodium and potassium also differed according to time. Despite the correlation between spontaneous salt appetite and small individual differences of plasma potassium concentration in normal sheep, deliberate induction of small changes in plasma potassium has no immediate effect on sodium appetite.