Journal of Applied Physiology, Vol 71, Issue 2 703-708, Copyright © 1991 by American Physiological Society
Effects of cold on microvascular fluid movement in the cat limb
J. X. Zhang and M. B. Wolf
Department of Physiology, University of South Carolina School of Medicine, Columbia 29208.
We investigated the effects of low temperatures down to approximately 5
degrees C on postcapillary resistance (Rv) and isogravimetric capillary
pressure (Pci) in the isolated constant-flow-perfused cat hindlimb to see
if a low-temperature-induced increase in Rv and decrease in Pci could lead
to an increase in filtration pressure and edema formation. A low-viscosity
perfusate (20% cat plasma, 80% albumin-electrolyte solution; viscosity
approximately 1 cP) was used. Isoproterenol (10(-7) M) was added to
vasodilate the limb and achieve normal microvascular permeability. Rv and
Pci were estimated from the slope and zero-flow intercept, respectively, of
the straight-line fit to the isogravimetric venous pressure vs. flow data.
Rv and Pci were determined in each experiment at an initial 37 degrees C
control, at a lowered temperature (30, 23, 15, or 5-10 degrees C), and then
at 37 degrees C again. The ratio of Rv at the low temperatures relative to
the initial 37 degrees C control increased almost linearly as temperature
was reduced. The increase was 3.4 times control at the lowest temperature.
Pci decreased significantly from control only in the lowest temperature
group where the change was -5.4 mmHg. Analysis of our data with the
low-viscosity perfusate shows that the limb can become edematous if
temperature is lowered to approximately 5 degrees C unless venous pressure
(Pv) is lowered to venous collapse and flow reduced to less than
approximately 20 ml.min-1.100g-1.(ABSTRACT TRUNCATED AT 250 WORDS)
