Blood pressure and fluid-electrolyte balance in mice with reduced
or absent anp.
John, S. W. M., A. T. Veress, U. Honrath, C. K. Chong, L. Peng, O.
Smithies, and H. Sonnenberg.
Department of Pathology, University of North Carolina, Chapel Hill,
NC, (current address: The Jackson Laboratory, Bar Harbor, ME), and
Department of Physiology, University of Toronto, Ontario, Canada
APStracts 3:0070R, 1996.
ANP-gene knockout mice of three genotypes [(+/+),(+/-) and (-/-)] were
maintained on a low salt diet (0.008% NaCl). They were then fed
either the same low salt diet or a high salt diet (8% NaCl) for 1
week. No differences were found among genotypes in daily food and
water intakes, or in urinary volume and electrolyte excretions.
Arterial blood pressures measured in anesthetized animals at the end
of the dietary regimen were significantly and similarly increased in
(-/-) compared to (+/+) mice on each diet. Renal excretion of fluid
and electrolytes was measured in anesthetized mice before and after
acute blood volume expansion. No genotype differences were observed
before volume expansion. After volume expansion the wild type (+/+)
mice had much greater saluretic responses than either the
heterozygous (+/-) or the homozygous mutant (-/-) animals on the low
salt diet but not on the high salt diet. We conclude that: ANP lowers
blood pressure in the absence of detected changes in renal function;
ANP is not essential for normal salt balance, even on high salt
intake; ANP is essential for the natriuretic response to acute blood
volume expansion on a low salt intake but not on high salt.
Received 21 August 1995; accepted in final form 31 January 1996.
APS Manuscript Number R521-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 March 96