RENAL AND SALIVARY RESPONSES TO INFUSION OF POTASSIUM CHLORIDE, BICARBONATE AND PHOSPHATE IN MERINO SHEEP

Abstract

The excretion of electrolytes was measured during infusion of isosmotic NaCl and hyperosmotic NaCl, KCl, KHCO3 and KH2PO4. The increases in G.F.R., urine flow and urinary excretion of potassium, sodium, chloride, bicarbonate and solute during the infusion of potassium salts were significantly greater than those during the isosmotic and hyperosmotic NaCl infusions; this finding excludes the rate of infusion and hyperosmolality of infusate as major contributors in the response to potassium infusion. The renal clearance of potassium was significantly higher in the sheep receiving the bicarbonate salt than in the animals receiving the chloride or the phosphate salts. Potassium bicarbonate loading was associated with low chloride excretion and potassium phosphate loading with low bicarbonate excretion. Potassium loading resulted in high rates of bicarbonate excretion in some experiments, which indicates a reduction in solute reabsorption in the proximal tubule. During the potassium infusions, the urinary calcium excretion rate and urinary pH were inversely correlated, renal magnesium excretion was not altered significantly and phosphate excretion was increased only when phosphate was infused. Salivary potassium secretion was highest in the phosphate‐loaded sheep and potassium retention was lowest in the sheep receiving KCl infusions.