The present study was undertaken to determine whether
trandolaprilat, an active form of
angiotensin I converting enzyme (
ACE) inhibitor, may improve
ischemia/reperfusion-induced contractile dysfunction and metabolic derangement of isolated rat hearts.
Ischemia (25 min) and subsequent 60-min reperfusion resulted in a small recovery of post-ischemic left ventricular developed pressure (LVDP), a sustained increase in left ventricular end-diastolic pressure, an increase in the release of
creatine kinase and
ATP metabolites from the perfused heart, and changes in myocardial
sodium,
potassium,
calcium and
magnesium contents. Treatment with 10-100 microM of
trandolaprilat for the last 10 min of pre-
ischemia recovered approximately 50-90% of pre-ischemic LVDP during reperfusion, whereas that with 30-100 microM of
enalaprilat restored approximately 55-65% of the pre-ischemic LVDP. Treatment with either
trandolaprilat or
enalaprilat at these concentrations attenuated the release of
creatine kinase and
ATP metabolites into the perfusate during reperfusion. Treatment with 30 microM
trandolaprilat suppressed
ischemia/reperfusion-induced changes in myocardial ion content. Treatment with
bradykinin during the last 10 min of pre-
ischemia also resulted in a post-ischemic contractile recovery with a degree similar to that of the
trandolaprilat-treated hearts.
E4177, an AT1-antagonist, showed no effect on
ischemia/reperfusion-induced changes in cardiac parameters. The enhancement of post-ischemic contractile recovery by the
ACE inhibitor was abolished by treatment with either
Hoechst 140, a
bradykinin (BK2) antagonist, or
diclofenac, a
cyclooxygenase inhibitor. These results suggest that
trandolaprilat is capable of attenuating
ischemia/reperfusion injury of isolated perfused hearts and altered BK metabolism is, at least in part, involved in this effect.