Effect of potassium on renal vascular resistance and urine flow rate

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Abstract
The effect of potassium chloride upon renal vascular resistance and urine flow rate was studied in anesthetized laparotomized dogs. Potassium chloride was infused directly into the renal artery with the rate of blood flow to the kidney held constant and with flow rate not controlled. Resistance progressively decreased when serum potassium level in the kidney was elevated by infusing 0.11–0.69 mEq K+/min. It progressively increased when the infusion rate exceeded 0.69 mEq/min. This relationship was unaltered by the adrenergic blocking agent phentolamine. Urine flow rate increased both before and after denervation of the kidney when potassium was infused at the rate of 0.6 mEq/min. This increase was not apparent when the rate of blood flow was held constant. These findings indicate that a local potassium excess in amounts which might occur naturally leads to dilatation of renal vessels and increase of urine flow rate. The latter probably is related to the former.