Cellular swelling and irreversible myocardial injury. Effects of polyethylene glycol and mannitol in perfused rat hearts.

Irreversible injury was produced in Langendorf-perfused rat hearts by 60 minutes of hypoxic, substrate-free perfusion at 37 C. Upon reoxygenation, hearts suddenly released large amounts of creatine phosphokinase (CPK) and over 60% of cells contained contraction bands and appeared irreversibly injured by light and electron microscopic criteria. Ten percent polyethylene glycol (PEG) or mannitol (420 mOsmol/liter) prevented or reduced swelling of rat heart slices incubated in vitro in the cold or under anoxic conditions. Both PEG and mannitol inhibited oxygen-induced CPK release after 60 minutes of hypoxia. Cells from protected hearts contained contraction bands but remained structurally intact. The results of this study provide evidence that cell swelling may play an important role in the pathogenesis of oxygen-induced enzyme release and irreversible myocardial cell injury.