AIM:To observe the effect of glycine liposomes on the mitochondrial membrane potential and the apoptosis rate in cardiomyocytes induced by hypoxia/reoxygenation injury.METHODS:A cardiomyocyte injury model was established by using hypoxia/reoxygenation.DiOC6(3)as fluorescence molecular probe was used to detect the mitochondrial membrane potential in each group.The method of Annexin V associated with PI was used to detect the apoptosis ratio in each group.RESULTS:(1)The result of flow cytometry showed that the mitochondrial membrane potential of cardiomyocytes in H/R group was obviously lower than that in control group(P0.01).The decrease in mitochondrial membrane potential in Gly-liposome group was the lowest,the percentage of cells about the part of hypofluorescence was(9.61±0.76)%,which was lower than that in glycine group(P0.01).(2)The apoptosis rate of cardiomyocytes in H/R group was higher than that in control group(20.78±1.58)%,P0.01.After the treatment of Gly-liposome,the apoptosis rate of cardiomyocytes was lower than that in glycine group(P0.01).No difference in the apoptosis ratios between blank-liposome group and H/R group was observed(P0.05).CONCLUSION:Glycine liposomes protect cultured cardiomyocytes against hypoxia/reoxygenation injury.Glycine liposomes produce the better protective effects than glycine.

AIM: To study the expression of glycine receptor (GlyR) in adult rat cardiac tissue and cultured cardiomyocytes from neonatal rat hearts. METHODS: Total RNA and membrane protein were extracted from cardiac tissue of adult rats and primary cultured cardiomyocytes from neonatal rat hearts, α1 and β subunits mRNA and protein of GlyR were detected with the method of reverse transcription nest DNA polymerase chain reaction (RT-PCR) and Western blotting. RESULTS: The mRNA and protein expression of β subunit were identified in the adult rat heart tissue and cultured cardiomyocytes, similar to the sequence and immunogenicity generated from GlyR β subunit of the rat spinal cord; for α1 subunit, mRNA was found in only cultured cardiomyocytes. CONCLUSION: These data demonstrate that adult rat cardiac tissue and cultured cardiomyocytes from neonatal rat hearts express mRNA and protein of GlyR subunits similar to the GlyR that expresses in the spinal cord, suggesting that GlyR exists in the membrane of the rat cardiomyocytes.

AIM: To investigate whether glycine receptor is involved in the protection of glycine against(anoxia/reoxygenation) injury in cardiomyocytes by detecting oxygen free radical metabolism,apoptosis and intracellular calcium overload.METHODS: The neonatal rat cardiomyocytes were cultured and exposed to anoxia and reoxygenation((A/R)) in the presence of glycine receptor antagonist,glycine or in free chloride buffer.The superoxide dismutase(SOD) activity,the contents of malondialdehyde(MDA) and nitric oxide(NO),the intracellular free calcium concentration and the apoptotic rate in the cardiomyocytes were determined.RESULTS: SOD activity and NO content in cardiomyocytes were lower,but MDA content,intracellular free calcium concentration and apoptotic rate in cardiomyocytes were higher in A/R group than those in control.Pretreatment with glycine inhibited the above changes caused by A/R,which was reversed by strychnine treatment and in the free chloride medium.CONCLUSIONS: Glycine inhibits free radical production,attenuates calcium overload,decreases apoptotic rate and increases SOD activity and NO release in cardiomyocytes exposed to(A/R).These findings suggest that glycine exerts a protective effect against A/R injury via glycine receptor and glycine protects the neonatal rat cardiomycytes from A/R-induced injury in a chloride-dependent manner.