AJP - Regulatory, Integrative and Comparative Physiology, Vol 235, Issue 5 237-R242, Copyright © 1978 by American Physiological Society
Body fluid distribution in wild Mus musculus acclimated to water restriction
H. Haines, T. M. McKenna and J. E. Melton
Total body water (TBW), extracellular volume (ECV), and plasma volume (PV)
were measured in wild house mice acclimated to chronic water shortage and
compared to the same measures in mice exposed acutely to water shortage.
Chronic mice were either steady state (SS), i.e., completely acclimated, or
nonsteady state (NSS), i.e., transitional. Water shortage was imposed
sequentially--1/2, 1/4, and 1/8 ad lib., and no water. SS mice lost solids
and cellular fluid at each level of restriction, but maintained plasma
volume and partially defended extracellular volume. Acute restriction to
1/2, 1/4, and 1/8 ad lib. caused proportional losses of solids and fluids
with the predominant fluid loss being extracellular. Acute restriction to
no water caused cellular dehydration plus a loss of extracellular fluids
including plasma. Comparison of acute and NSS mice at identical levels of
restriction showed the NSS groups to be preacclimated toward further water
restriction. Discussion centers on the comparison of acclimated and
nonacclimated animals, mechanism of PV defense, and the general process of
acclimation.
