Early adaptations in collateral and microvascular resistances after
ligation of the rat femoral artery.
Unthank, Joseph L., J. Craig Nixon, and Julia M. Lash.
Departments of Surgery and Physiology and Biophysics, Indiana
University Medical Center, Indianapolis, IN 46202
APStracts 2:0082A, 1995.
Collateral and microvascular (including feed artery) resistances in
the rat hindlimb were determined immediately or 1 week after ligation
of the femoral artery. Collateral:microvascular resistance ratios
were determined from in vivo pressure measurements proximal and
distal to the ligation. Microvascular resistance was 32+/-2.5 and
41+/-1.5% of the total collateral dependent vasculature in acutely
and chronically ligated limbs, respectively, and decreased 20% in
both groups during reactive hyperemia. Minimum resistances of
collateral vessels and the microcirculation arising from arterial
branches proximal and distal to the ligation were determined using a
modification of the standard hindquarter perfusion technique for
determining maximum vascular conductance. One week post-ligation,
minimum total hindquarter resistance was decreased by a reduction in
the resistance of collaterals (50%) and the microcirculation (33%)
proximal to the ligation. The results suggest that the
microvasculature distal to the occlusion is able to increase flow by
dilation both initially and at 1 week post-ligation, but that
collateral adaptations are primarily responsible for decreases in the
minimum total resistance of the collateral-dependent region.
Received 19 July 1994; accepted in final form 27 February 1995.
APS Manuscript Number A736-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 10 March 1995.