The trolox analog, U-78517F, attenuates hypoxic injury in isolated cardiac myocytes

Neonatal rat cardiac myocytes were subjected to 5 h of hypoxia (PO2 < 5 mmHg) in glucose-free, modified Tyrodes solution. Prior to hypoxic exposure, cells were pretreated for 90 min with media alone or containing the trolox analog, U-78517F, at 0.3, 1, or 3 microM. Hypoxic injury was characterized by a significant loss of sarcolemmal integrity [76 +/- 12% of the total cell fluorescence (mean +/- S.E., n = 14 cultures)] quantified by nuclear staining with the membrane-impermeant fluorophore propidium iodide. In addition, hypoxia also induced significant decreases in the intracellular content of Creatine Kinase (43 +/- 7%, n = 12), Lactate Dehydrogenase (25 +/- 5%, n = 8), adenosine 5'-triphosphate (49 +/- 12%, n = 6), and sulfhydryls (34 +/- 4%, n = 6). Sarcolemmal integrity was significantly preserved by pretreatment with 1 microM and 3 microM U-78517F which reduced propidium iodide staining below the hypoxic control value by 51 +/- 9% (n = 12) and 75 +/- 4% (n = 14, P < 0.01 v hypoxic control), respectively. Similar results were obtained in cells pretreated with alpha-tocopherol suggesting that these two compounds are equipotent at preserving the sarcolemmal integrity of cardiac myocytes exposed to hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)