Increased nacl preference of rats fed low-protein diet.
Okiyama, Atsushi, Kunio Torii, and Michael G. Tordoff.
Monell Chemical Senses Center, 3500 Market St., Philadelphia PA
19104-3308, USA, Food Research and Development Laboratories Ajinomoto
Co., Inc., Kawasaki, Kanagawa 210, Japan, and Torii Nutrient-Stasis
Project, Exploratory Research for Advanced Technology Research
Development Corporation of Japan, Yokohama, Kanagawa 221, Japan
APStracts 3:0010R, 1996.
Four studies were conducted to assess the effect of a low-protein diet
on NaCl intake. Young rats fed either control (20% casein) or low
-protein (5% casein), high carbohydrate (CHO) diet were given to drink
either water alone or water and 300 mM NaCl. Relative to rats fed
control diet, rats fed the low-protein diet progressively increased
NaCl intake so that, despite lower food and water intakes, they drank
180% more NaCl during the last 3 days of the 21-day test. Additional
studies found that rats fed low-protein diet always maintained
positive sodium balance, were neither sodium-depleted nor
hypovolemic, and had normal plasma renin activity and aldosterone
concentrations. The elevated NaCl intake was not secondary to calcium
deficiency, and was unaffected by mineral supplementation of the
protein-deficient diet. Increases in the diet's CHO and/or fat
content incidental to decreases in its protein content influenced,
but could not completely account for, the effect of protein
deficiency on NaCl intake. We conclude that protein deficiency is the
primary cause of the elevated NaCl preference produced by feeding a
low protein diet, and that a novel physiological mechanism underlies
this behavior.
Received 21 June 1995; accepted in final form 11 December 1995.
APS Manuscript Number R380-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 22 January 96