Renal potassium excretion in sheep during sodium sulfate, phosphate, and chloride infusion

The renal excretion of potassium by unanesthetized sheep was studied in clearance studies in which water and sodium excretion were elevated by intravenous infusion of isotonic sodium chloride, hypertonic sodium phosphate, or hypertonic sodium sulfate. Aldosterone was infused at 10 microgram/h in some experiments with sodium sulfate. Sodium excretion increased in all experiments, rising at times to equal 25% of the filtered load. Urine flow increased in most experiments. Glomerular filtration rate increased only with infusion of isotonic saline. No consistent change in potassium excretion occurred under any of these loading conditions. This finding contrasts with the increase in potassium excretion commonly seen in man, dogs, and rats intravenously loaded with sodium salts.