Failure of aortic cross clamping to cause renal cortical blood flow redistribution and increased renin release

The present study was undertaken to examine renal cortical blood flow distribution during aortic cross clamping, and utilizes the microsphere technique, a direct measurement of renal cortical blood flow. With the aorta cross clamped, there was an increase in renal vascular resistance, but no redistribution of renal cortical blood flow, and increased renal renin release was demonstrated which is at variance with previously published data. In the present studies a direct method for measuring the distribution of renal cortical blood flow was used which did not depend on the xenon washout method and allowed blood flow measurements to be made without manipulation of the renal arteries. In addition, hematocrit, blood pressure, and serum sodium values remained close to control levels and presumably should not alter intra renal hemodynamics.