Characterization of microvascular vasoconstriction following ischemia/reperfusion in skeletal muscle using videomicroscopy

This study investigated the possible contribution of microvascular vasoconstriction to no-reflow following ischemia/reperfusion in a mouse skeletal muscle model. Using paired cremaster muscles, arterioles of diameter 10-100 microns were directly viewed and measured by the use of an in vivo videomicroscopy before and after a 6-hr period of complete ischemia at 27 degrees C. Following ischemia/reperfusion, feeder and arcading arterioles constricted significantly to 54.5 and 62% of pre-ischemic baseline diameters respectively (P < .05). While the calcium antagonist diltiazem and nitroprusside were both able to reverse arteriolar constriction, endothelium-dependent acetylcholine-induced dilatation was markedly impaired following reperfusion (P < 0.05). Superoxide dismutase did not attenuate the microvascular response, suggesting that the mechanism is likely to be at least partly free radical-independent.