Phenol Red Clearances in the Dog

Abstract

Marshall and his coworkers1 were the first to adduce evidence that phenol red is excreted by the dog's kidney by tubular secretion as well as by glomerular filtration. This evidence was: (1) phenol red injected intravenously accumulated in the cells of the convoluted tubules of the anuric kidney obtained by spinal transection; (2) phenol red is in part bound to plasma colloids and thus rendered non-filtrable, and an insufficient concentration of filtrable phenol red is present in arterial blood to account for the quantity excreted in the urine; (3) in two experiments on anesthetized dogs the rate of excretion of phenol red was not proportional to the concentration in the plasma at all levels of the latter; (4) phenol red clearances in a normal dog were considerably greater than simultaneous creatinine clearances. The last mentioned experiments were done within a restricted range of plasma phenol red (0.21 to 0.54 mg. %) and leave undetermined the question of the relationship of the latter to the phenol re...