Simultaneous measurement of renal blood flow of the outer and inner cortex by laser-Doppler flowmetry in anesthetized dogs: effect of enalapril diacid.

Renal hemodynamic effects of the angiotensin-converting enzyme inhibitor enalapril diacid (30 micrograms/kg, i.v.; n = 8) were examined using laser-Doppler flowmetry in anesthetized dogs. Two laser-Doppler flowmetry probes were applied simultaneously to measure the renal blood flow of the outer and inner cortex. Changes in cortical renal blood flow, obtained by the laser-Doppler flowmetry method, were intimately related to those in total renal blood flow measured with the electromagnetic flow probe during occlusion of the abdominal aorta or after administration of angiotensin II, norepinephrine, acetylcholine or dopamine. Enalapril diacid produced a significant increase in total renal blood flow, despite moderate hypotension. The blood flow of the inner cortex significantly increased by 21% following enalapril diacid, while that of the outer cortex did not. These data indicate that there may be a regional difference in the intrarenal vasodilating effect of enalapril diacid. These results also demonstrate that the laser-Doppler flowmetry method is suitable for the continuous measurement of directional changes in both outer and inner cortical blood flows.