Effect of WY-5256 on Renal Hemodynamics

WY-5256 was administered to dogs to determine the effect of this agent on renal hemodynamics. Changes in renal hemo-dynamics were estimated with an electromagnetic flow meter in conjunction with clearances of p-aminohippurate (PAH) and inulin. It was observed that WY-5256 increased renal blood flow, that the increase was greater than that indicated by PAH calculated blood flow, and that increases in non-PAH extracting flow were greater in proportion than increases in PAH calculated blood flow. The effect of WY-5256 on renal function was also studied when renal blood flow was held constant with an aortic clamp. It was demonstrated that the drug increased sodium excretion in the absence of blood flow alterations. The increase was less than that seen without the clamp. These data are interpreted as indicating that this agent acts in part by directly inhibiting sodium reabsorption and in part by altering renal hemodynamics to increase sodium excretion.