Protection of Glycyl-L-Glutamine against myocardial ischemia-reperfusion injury in the isolated rat heart

AIM: To study the protection of Glycyl-L-Glutamine(Gly-Gln) against myocardial ischemia/reperfusion(I/R) injury in the isolated rat heart.METHODS: A model of myocardial ischemia-reperfusion injury was established with a Langendorff apparatus. Thirty male SD rats were randomly divided into four groups: control group, Gly-Gln group, I/R group and I/R+Gly-Gln group. Both I/R and I/R+Gly-Gln group were pre-perfused for 30 min, followed by 20 min ischemia and 40 min reperfusion. During reperfusion I/R+Gly-Gln group was perfused with Gly-Gln perfusate. Control group was kept perfused for 90 min. Gly-Gln group Gly-Gln perfusate was also kept perfused for 90 min. The left ventricular end-diastolic pressure(LVEDP), left ventricular developed pressure (LVDP), ±dp/dtmax, heart rate (HR), monophasic action potentials(MAP) was measured during perfusion. The coronary effluent fluid was collected at different certain times. The activities of lactic dehydrogenase (LDH) and creatine kinase(CK) were determined.RESULTS: The isolated rat heart function decreased severely after 20 min ischemia and 40 min reperfusion(I/R): the LVEDP increased and the LVDP, ±dp/dtmax decreased. But the LVEDP decreased and the LVDP, ±dp/dtmax increased in I/R+Gly-Gln group compared with I/R group. Moreover, the activities of LDH and CK in the coronary effluent fluid decreased remarkably in I/R+Gly-Gln group compared with I/R group.CONCLUSION: Gly-Gln can play a protective role against myocardial I/R injury in isolated rat hearts via maintaining the left ventricular function and decreasing the release of LDH and CK.