AJP - Regulatory, Integrative and Comparative Physiology, Vol 272, Issue 6 1853-R1861, Copyright © 1997 by American Physiological Society
Epidermal growth factor and fluid and electrolyte balance in the rat
S. L. Grant, C. B. Gow and P. A. Phillips
Department of Medicine, University of Melbourne, Austin, Australia.
Epidermal growth factor (EGF) has been shown to induce a renal diuresis and
natriuresis in sheep and stimulate prostaglandin synthesis from inner rat
medullary collecting duct cells in culture. The aims of our study were 1)
to investigate whether the renal effects of intravenous infusion of EGF
were species specific and 2) to determine the mechanism of these effects by
studying the interaction between EGF and indomethacin (a prostaglandin
synthase inhibitor) in the conscious rat. Sprague-Dawley rats received
intravenous infusions of either 0.9% saline or 0.2 or 2.0 micrograms
EGF.kg-1.h-1 over a 6-day period after an initial baseline period. Infusion
of 2.0 micrograms EGF.kg-1.h-1 caused an increase in urine volume
(baseline: 5.5 +/- 0.2 ml to day 5: 9.0 +/- 0.4 ml, P < 0.01) and
corresponding polydipsia, but not natriuresis. Administration of
indomethacin with 2.0 micrograms EGF.kg-1.h-1 attenuated (P < 0.05) the
diuretic (day 5 EGF + vehicle: 12.2 +/- 1.1 ml vs. EGF + indomethacin: 8.7
+/- 0.9 ml) and polydipsic effects of EGF. These studies demonstrate that
intravenous infusion of EGF causes a diuretic effect in rats without
natriuresis and that prostaglandins play a role in the diuretic effect of
EGF in the rat.
