The Excretion of Xylose by Glomerular and Aglomerular Kidneys.

Abstract

Marshall in a comparative study of the function of the glomerular and aglomerular kidney found that glycosuria is easily produced in fish with glomerular kidneys, but only a trace of glucose ever appears in the urine from an aglomerular kidney, even when the blood sugar is high and phlorhizin is given. This observation with those of Corley and Fishberg on the rate of disappearance of xylose from the blood suggested that a foreign sugar such as xylose might serve as a basis for measuring the extent of filtration and reabsorption by the kidney. First it was necessary to establish that xylose is not excreted by the aglomerular kidney except in the very faintest traces. That is the object of this paper. Four species of fish were selected. The cod fish (Gadus callarias) and the puffer (Spheroides maculatus), fish with glomerular kidneys; the toadfish (Opsanus tau) and the goosefish (Lophius piscatorus), fish with aglomerular kidneys, were studied. The experiments on the goosefish were performed by Dr. E. K. Marshall, Jr., at Salisbury Cove, Maine. The other fish were obtained at the New York Aquarium. The urinary papilla was tied off and xylose in aqueous solution was injected into the posterior dorsal muscles in all experiments except those on the goosefish in which the xylose was injected intravenously. At the conclusion of the experiment, 1 to 23 hrs. later, the fish were sacrificed and the urine in the bladder obtained by dissection. A filtrate, using 1 cc. of urine (1 cc. of a 1-50 dilution in the puffer series), was prepared by Somogyi's method. Total sugar was determined on aliquot portions of this filtrate by the Hagedorn-Jensen Micro method. The rest of the filtrate was treated with washed baker's yeast as recommended by Van Slyke and Hawkins and the non-fermentable reducing substances determined on aliquot portions.