Abstract: The effect of carboxyethylgermanium sesquioxide (Ge-132) on culturedneonatal rat myocytes and isoproterenol injured myocytes was studied. The results showedthat Ge-132 (0. 01 mmnol.L^-1and 1 mmol.L^-1) increased the incorporation of both ³H-TdR and ¹⁴C-UR, reduced the membrane lipid fluidity and inhibital the release of thecytoplasmic enzyme lactate dehydrogenase (LDH). Exposure of the myocytes toisoproterenol 0.5 mmol.L^-1 for 6 hours resultal in 5-fold release of LDH comparedwith the control. All myocytes ceased beating. Ultrastucturally, severe sarcolemmal andmitochondrial damage was evident. When the cells were pretreated with Ge-132 beforethe addition of isoperterenol, the increased LDH release was idhibital significantly, andpreservation of beat and ultrastructure of myocytes was observed. In addition, the activityof superoxide dismutase (SOD) was elevated by Ge-132. All the effects of Ge-132 weredose-reated. The results indicate that Ge-132 may improve the metabolism of culturedneonatal rat myocytes and protect myocytes from isoproternol-induced injury.