This study was undertaken to test whether a brief period of ischemia affects the coronary pressure-flow relationship during reduction of coronary perfusion pressure (CPP). The left anterior descending coronary artery was cannulated and perfused with blood from the left carotid artery in 40 open-chest dogs. Coronary blood flow (CBF) was measured during intracoronary administrations of papaverine and adenosine. The coronary pressure-flow relationship was assessed during transient reduction of CPP from 100 to 30 mmHg. Coronary hyperemic flow due to adenosine and papaverine was attenuated 30 min after transient 10- and 15-min periods of ischemia. In the group of transient 10-min ischemia, both fractional shortening (FS) and CBF returned to the preischemic values at 30 and 60 min of reperfusion; however, marked decreases in CBF (35 +/- 5 vs. 56 +/- 4 ml.100 g-1.min-1 at CPP = 60 mmHg, P < 0.01) during graded reductions in CPP were observed. The endomyocardial blood flow was reduced relative to the control condition. Furthermore, both FS (6 +/- 1 vs. 14 +/- 1% at CPP = 60 mmHg, P < 0.01) and lactate extraction ratio (-41 +/- 15 vs. 1 +/- 6% at CPP = 60 mmHg, P < 0.05) were decreased. The downward shift of the CPP-CBF relationship and the deterioration of myocardial contractile and metabolic function during reduction of CPP were restored 60 min after the onset of reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)