Abstract
Summary
Renal excretion of water and solutes is enhanced during intraarterial infusion of various vasodilator drugs into the canine kidney, although the mechanism mediating increased excretion is uncertain. We studied effects of infusing dimaprit, acetylcholine, and prostacyclin into the left renal artery of anesthetized dogs. Blood flow in the vessel was estimated with an electromagnetic blood flowmeter. GFR was determined from the clearance of exogenously administered creatinine. Other estimated renal functions included excretion of chloride and total osmolytes. Infusion of each of the vasodilator drugs in doses which increased renal blood flow by approximately 50% caused significant increases in GFR, fractional and total chloride excretion, and total solute excretion. Both circulatory and excretory responses to dimaprit were virtually abolished by cimetidine. Dimaprit and prostacyclin appear to increase renal excretion of water and solutes mainly through their vasodilator actions, whereas acetylcholine also acts directly upon the renal tubule to enhance renal excretion. All three dilator agents increased glomerular filtration rate in our experiments.
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