(A) Coronary arteriolar vasoconstriction in response to the thromboxane A (TXA)-2 analog U-46619 before vs after cardioplegic ischemia, followed by reperfusion (pre-CP/Rep [white circles] vs post-CP/Rep [black circles]); *p < 0.05 vs pre-CP/Rep. (B) Administration of U-46619 with or without TXA-2 antagonist SQ-29548 to microvessels of pre-CP/Rep (U-46619 [pre-CP/Rep, white circles] or SQ-29548 + U-46619 [pre-CP/Rep, black squares]); *p < 0.05 vs U-46619 (pre-CP/Rep). (C) Infusion of U-46619, with or without the TXA-2 antagonist SQ-29548, to post-CP/Rep vessels (U-46619 [post-CP/Rep, black circles] or SQ-29548 + U-46619 [post-CP/Rep, black diamonds]); p < 0.05 vs U-46619 (post-CP/Rep); n = 6 to 8/group. The bars show the standard error of the mean.