The role of damage to myofibrillar proteins in reversibly hypocontractile myocardium has been examined in chronically instrumented dogs undergoing sustained partial coronary occlusion. Findings in six animals 24 hours following a five-hour flow reduction of ∼75% were consistent with myocardial stunning, i.e., regional sonomicrometric function remained depressed (57 ± 7[SEM]% of control) while myocardial O2 consumption had returned to control levels . Findings in seven additional animals following a two-hour 50% flow reduction were consistent with myocardial hibernation, i.e., regional function and myocardial O2 consumption were reduced proportionately, averaging 80 ± 4% and 85 ± 4% of control. Creatine kinase (CK) activity in myofibrils isolated from areas of reduced flow was reduced systematically in both situations. In "stunned" animals subendocardial and full-thickness CK activities averaged 69 ± 9 and 83 ± 10% of levels in normally perfused myocardium (both p<0.05). Corresponding values in "hibernating" animals were 76 ± 11 and 79 " 11% (both p<0.05). CK activity was also reduced in animals undergoing two- or five-hour flow reductions without reperfusion. The CK reductions in both settings emphasize the complexity of responses to flow reduction, as well as limitations of the dichotomous characterization of post-ischemic contractile dysfunction as hibernating or stunned.
|Original language||English (US)|
|State||Published - Mar 20 1998|
ASJC Scopus subject areas
- Molecular Biology