Journal of Applied Physiology, Vol 44, Issue 4 585-588, Copyright © 1978 by American Physiological Society
Acute dehydration: body water distribution in acclimated and nonacclimated Psammomys obesus
M. Horowitz, S. Samueloff and J. H. Adler
Body water distribution after "acute dehydration" treatment (37 degrees C)
was studied in Psammonys obesus before and after acclimation at 34 +/- 1
degrees C for 16-18 days. Determinations of water compartment volumes were
performed on anaesthetized (thiopental sodium) nephrectomized animals.
Plasma volume (PV) and extracellular volume (ECV) were measured by T-1824
and [14C]inulin, respectively. Total body water was determined after
desiccating the animals. Albumin outflux was calculated from the half-life
(T1/2) of T-1824 and total plasma albumin mass. Nonacclimated animals
conserved PV as long as dehydration did not exceed 10-11% loss of body wt.
This conservation was at the expense of ECV and was associated with
diminished albumin outflux (T1/2 T-1824 approached infinity). With
increased dehydration PV retention failed and a resumption of albumin
outflux occurred. Acclimation resulted in diminished albumin outflux in
both control and dehydrated animals (T1/2 T-1824 approached infinity). Most
of the water lost during dehydration was of intracellular origin. It was
concluded that reduction in permeability of the capillary bed during
dehydration and acclimatization plays an important role in PV and ECV
regulation.
