CAPILLARY PERFUSION DURING ISCHEMIA-REPERFUSION IN SUBCUTANEOUS CONNECTIVE-TISSUE AND SKIN MUSCLE

Ischemia-reperfusion injury was investigated in terms of functional ca pillary density (FCD), capillary red blood cell velocity (cRBCv), and arteriolar and venular diameter after 4-h ischemia in the unanesthetiz ed hamster skin-fold preparation. Animals in group 1 were studied by t ransillumination. Group 2 received a bolus injection of fluorescein is othiocyanate (FITC)-dextran (mol wt 150,000) and was studied by transi llumination (zone 1) and epi-illumination (zone 2). In group 1, FCD de creased after ischemia (92% of baseline, 30 min), returning to control up to 24 h. cRBCv increased after reperfusion, being 175% of baseline at 24 h. Arterioles and venules dilated for 24 h after reperfusion. I n group 2/zone 2, FCD progressively decreased to 11% of control, arter iolar dilation was inhibited, and cRBCv increased 30 min and 2 h after reperfusion. Tissue perfusion index (FCD x cRBCv) increased 158% in g roup 1 at 24 h, did not change in group 2/zone 1, and was 9% of contro l at 24 h in group 2/zone 2 (P less than or equal to 0.05). We conclud e that increased perfusion is a normal reaction to ischemia-reperfusio n injury in this model, and previously observed capillary no reflow is due to FITC-dextran phototoxicity.