Early adaptations in collateral and microvascular resistances after ligation of the rat femoral artery.
Collateral and microvascular (including feed artery) resistances in the rat hindlimb were determined immediately or 1 wk after ligation of the femoral artery. Collateral-to-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 by using a modification of the standard hindquarter perfusion technique for determining maximum vascular conductance. One week postligation, minimum total hindquarter resistance was decreased by a reduction in the resistance of the collaterals (approximately 50%) and microcirculation (approximately 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 wk postligation but that collateral adaptations are primarily responsible for decreases in the minimum total resistance of the collateral-dependent region.
Unthank
J L
JL
Department of Surgery Indiana University Medical Center, Indianapolis 46202, USA.
Nixon
J C
JC
Lash
J M
JM
D000222:Adaptation, Physiological; D000818:Animals; D001775:Blood Circulation; D001794:Blood Pressure; D003097:Collateral Circulation; D005263:Femoral Artery / Q000502:physiology*; D008026:Ligation; D008297:Male; D008833:Microcirculation; D008954:Models, Biological; D010477:Perfusion; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D014655:Vascular Resistance