APStracts 2:0054F, 1995.

Influence of glucagon on gfr, and on urea and electrolyte excretion: direct and indirect effects. Ahloulay, Mina, Mich[grave]ele D[acute]echaux, Kathleen Laborde, and Lise Bankir. INSERM Unit[acute]e 90, H[circumflex]opital Necker-Enfants Malades, 75743 Paris Cedex 15, France, Laboratoire de Physiologie, CHU Necker -Enfants Malades, 75743 Paris Cedex 15, France, D[acute]epartement de Biologie, Facult[acute]e des Sciences, Universit[acute]e Choua[diaeresis]ib Doukkali, El Jadida, Maroc

APStracts 2:0054F, 1995.

Clearance experiments were performed in anesthetized male Wistar rats in order to determine the level of peripheral glucagon (G) concentration required to elicit changes in GFR and in solute excretion. Glucagon was infused i.v. at a rate of 1.25 (G1, n = 8), 3.75 (G3, n = 7), or 12.5 (G10, n = 7) ng/min x 100 g BW, for 100 min. Measurements were performed before, during, and after this infusion. G10 resulted in a plasma concentration of G several fold higher than usually observed after a protein meal in peripheral blood, but normal for the hepatic circulation. G10 increased simultaneously GFR, plasma cAMP concentration, and the excretion of water (V), Na, Cl, PO4, K, and urea. Some of the effects of G on electrolyte excretion were also observed with G1 and/or G3 and were fully reversible, suggesting a direct renal action of G. The significant and reversible increase in K excretion in group G3 suggests that G exerts a direct stimulatory influence on K secretion in the distal nephron. Increases in V, and in PO4, Na, and urea fractional excretions were seen with G10 only and were not reversible, suggesting an indirect action of G on the proximal tubule. Because G stimulates cAMP formation in hepatocytes, and because this cAMP is released in the blood and secreted by proximal tubule cells, cAMP of hepatic origin could induce a PTH-like effect in this nephron segment. In summary, these experiments suggest that glucagon influences different aspects of renal function by a combination of direct and indirect (probably liver-dependent) effects.

Received 11 August 1994; accepted in final form 5 April 1995.
APS Manuscript Number F285-4.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 April 1995.