EFFECTS OF GM1 GANGLIOSIDE ON CARDIAC-FUNCTION FOLLOWING EXPERIMENTALHYPOXIA-REOXYGENATION

Rat hearts made hypoxic for 20 min by perfusion with 95% N2/5% CO2 and reoxygenated for 20 min in a Langerdorff apparatus showed a dose-depe ndent reduction of lactate dehydrogenase release when incubated with g anglioside GM1 (0.1-10 muM). The decline of contractile force during h ypoxia was also reduced dose dependently in the presence of GM1. Simil ar effects were observed in hearts obtained from animals treated i.p. with 40 mg/kg GM1 for 14 days. The levels of Na+,K+-ATPase in ventricu lar tissue were also reduced after hypoxia-reoxygenation and the reduc tion was prevented in hearts from GM1-treated animals. GM1 (1-30 muM) reduced the functional response to field stimulation of adrenergic ner ve terminals in isolated atria. Rat atria made hypoxic in glucose-free media maintained normal stores of tissue noradrenaline in the presenc e of 1 muM GM1. In the rabbit, GM1 (40 mg/ kg i.p. for 4 days) reduced the alterations of the ST segment of the ECG during acute occlusion o f the left descending and circumflex coronaries artery. In conclusion, ganglioside GM1 reduces some effects of hypoxia-reoxygenation in the heart, through still unknown mechanisms.