AJP - Heart and Circulatory Physiology, Vol 245, Issue 1 159-H166, Copyright © 1983 by American Physiological Society
Temperature effects on dog hindpaw series and parallel vascular circuits
C. H. Baker, D. L. Davis, B. G. Lindsey and E. T. Sutton
The effect of environmental temperature (skin surface) on distribution of
blood flow between the parallel vascular circuits has been assessed in
vascularly and neurally isolated hindpaws perfused at constant pressure.
The paw was sealed in a chamber filled with water at 10, 20, 30, or 40
degrees C. Peripheral resistance increased as the temperature decreased in
both innervated and denervated paws. Resistance in the denervated paws was
less than in the innervated paws at all temperatures. Recovery of 85Sr
microspheres was less at 40 degrees C than at 10, 20, or 30 degrees C in
the denervated paws but did not change in innervated paws. Capillary
availability (diffusion capacity and filtration coefficient) increased with
each elevation in temperature in both groups. At 10 degrees C both
arteriovenous (AV) shunt and capillary flows were low in innervated paws
with low capillary and high shunt flow in denervated paws. At 20 and 30
degrees C capillary flow increased with temperature and arteriovenous
anastomosis (AVA) flow was unchanged in denervated paws. In innervated paws
AV shunt flow fraction slightly increased, with capillary perfusion
markedly increased as temperature was elevated. The increased capillary
flow in both groups passed through an enlarged capillary bed, whereas the
number and/or diameter of AVAs remained essentially unchanged.
