Interactions in the renal handling of inorganic phosphate and glucose in sheep. (Abstract)

Abstract

192 Interaction in the Renal Handling of Inorganic Phosphate and Glucose in Sheep. T. Schalk and I.R. Godwin Department of Physiology, School of Rural Science, University of New England, Armidale, N.S.W. 235 1. In non-ruminants it has been observed that glucose decreases the reabsorptive capacity for inorganic phosphate (Pi) (Ginsburg, 1972). The present study was undertaken to observe whether this interaction occurs in sheep, a species that normally has plasma concentrations of both Pi and glucose below their tubular maxima (Tm) for reabsorption. ! Six merino ewes were fed a mixed ration of lucerne and oaten chaff. They were infused intravenously with saline, glucose, Pi and glucose and Pi solutions in a latin square design. Renal clearances for glucose, Pi and creatinine were determined every 30 mins for 4 h. Tubular maxima were determined from plots of tubular load versus renal clearance. The Tm for glucose was not affected by the infusions, however the Tm for Pi was greatly enhanced by the presence of a high tubular load for glucose (see Fig. 1 and 2). We suggest this effect may be due to an action of insulin on tubular Pi reabsorption in sheep, a species in which insulin plays some role in electrolyte metabolism (Beal 1979) References Beal, A.M (1979) Aust.J.Biol.Sci. 32.~ 353-357. Ginsburg, J.M. (1972) Am.J. Physiol. 222: 1 I .53- I I60 Figure 1 The effects of glucose on the Tm for Pi. Figure 2 The effects of Pi on the Tm for glucose. Recent Advances in Animal Nutrition in Australia: July 1995 University of New England, Armidale NSW 23.51, Australia