AJP - Regulatory, Integrative and Comparative Physiology, Vol 261, Issue 1 188-R197, Copyright © 1991 by American Physiological Society
Renal, hormonal, and fluid shift responses to ANP during head-out water immersion in awake dogs
J. A. Krasney, M. Carroll, E. Krasney, J. Iwamoto, J. R. Claybaugh and S. K. Hong
Department of Physiology, School of Medicine and Biomedical Sciences, State University of New York, Buffalo 14214.
Renal responses to low doses of atrial natriuretic peptide (ANP) may be
potentiated during water immersion-induced central hypervolemia. To test
this hypothesis, ANP was infused in awake dogs in doses of 0, 5, and 25
ng.kg-1.min-1 either when the dogs were in air or during head-out water
immersion (WI) under thermoneutral conditions (37 degrees C). In general,
there were greater diuretic (V) and natriuretic responses (UNaV) at the
same level of plasma ANP in WI, with the slopes (or sensitivities) of V and
UNaV in relation to plasma ANP levels being significantly increased during
WI. Plasma renin activity decreased only during WI and was significantly
correlated with both V and UNaV only during WI. Plasma and urinary arginine
vasopressin levels were unchanged during WI. Infusion of ANP prevented the
usual decline of hematocrit that occurs during WI. These results support
the view that the renal sensitivity to ANP is augmented during the plasma
volume expansion of WI. In addition, ANP may attenuate the transcapillary
fluid shift that occurs during WI.
