FACTORS INFLUENCING THE LABILITY OF HUMAN RENAL BLOOD FLOW.

Abstract

0 xygen and other metabolite transport is a yprimary function of blood, but the peculiar relationship of renal functional capacity to blood volume flow and pressure is expressed in terms of glomerular filtration, tubular transport, renin production,3 and probably other metabolic activities. In the normal young adult in a state of rest, and with a hydration/urinary output ratio in excess of 2 ml. per minute, at least 25 percent of the cardiac output perfuses approximately 300 Gm. of renal tissue; this is equivalent to 600 ml. of blood flow per minute per kidney. The Olympic sprinter may temporarily reduce renal blood flow to the point of anuria. Between these compensatory values are all patients who have obstructive disease of the renal arteries, renal transplantation, anesthesia, or other conditions which alter renal blood flow. Adequate perfusion of the renal vascular system requires definition in scientific terminology relating renal mass, mainstem arterial pressure, and peripheral resistance as equated to volume flow in time. Clearance ratios and tubular maxima, measured by either chemical or radioisotope techniques, are our best indices of renal functional capacity, but for purposes of the surgeon they have limitations: They are not technically applicable within the time and