THE EFFECT OF URANIUM POISONING ON PLASMA DIODRAST CLEARANCE AND RENAL PLASMA FLOW IN THE DOG

Abstract

Inulin, creatinine, urea, and diodrast clearances were studied in dogs with explanted kidneys both before and after U poisoning. Following poisoning, all clearances are reduced. Diodrast clearance falls to the level of inulin clearance and is no longer a measure of renal blood flow which remains unchanged. The reduction in clearances is best explained on the basis of extensive back diffusion of these substances through the damaged tubule. Tubular diodrast plasma clearance and Tm fall to zero or negative values indicating replacement of tubular secretion by some tubular back diffusion. The filtration fraction (inulin clearance/diodrast clearance) approaches unity and is of no significance since diodrast clearance is no longer a measure of plasma flow. Tubular damage may be an important factor in the high filtration fractions observed in certain types of kidney injury.