LOSS OF SUPERFICIAL FEMORAL-ARTERY RELAXATION FOLLOWING ISCHEMIA-REPERFUSION

Acute ischemia followed by reperfusion in skeletal muscle is associate d with tissue edema and necrosis. The purpose of this study was to dem onstrate superficial femoral artery endothelial injury following compl ete ischemia with reperfusion. New Zealand white rabbits underwent tot al devascularization of one hindlimb for 3 hr followed by 0, 1, and 2 hr of reperfusion. Control rabbits underwent a sham operation. Superfi cial femoral artery rings were then studied for acetylcholine induced relaxation in vitro. The response to acetylcholine was measured as per centage relaxation at three incremental doses (1 x 10(-7), 3 x 10(-7), and 5 x 10(-7) M). The ischemia-only (26.30 +/- 7.07, 62.63 +/- 8.64, 88.08 +/- 5.25%) and the l-hr reperfusion group (19.35 +/- 12.99, 39. 24 +/- 15.78, 62.01 +/- 14.03%) showed no significant difference (P gr eater than or equal to 0.05, Student's t test) in relaxation as compar ed to the control group (13.73 +/- 2.11, 47.88 +/- 7.23, 72.44 +/- 9.0 0%). The 2-hr reperfusion group (6.10 +/- 1.02, 15.33 +/- 2.56, 34.67 +/- 6.31%), however, had a significant loss of relaxation at all three doses of acetylcholine compared to that seen in the control group (P greater than or equal to 0.05, Student's t test). In this model of com plete ischemia, superficial femoral artery rings lose their ability to relax in response to acetylcholine following 3 hr of ischemia and 2 h r of reperfusion, demonstrating endothelial injury. However, immediate ly after 3 hr of ischemia or ischemia followed by only 1 hr of reperfu sion, superficial femoral artery rings did not lose their ability to r elax in response to acetylcholine. This study identifies a window of o pportunity for therapeutic intervention after ischemia and prior to en dothelial injury from reperfusion. (C) 1996 Academic Press, Inc.