[Protective effect of glycine on hypoxic rat myocardial cells].
OBJECTIVE
To investigate the protective effect of glycine (Gly) on hypoxic rat myocardial cells and its mechanism.


METHODS
Sdfetal rat myocardial cells were isolated and cultured in vitro. The released amounts of creatine kinase (CK) and lactate dehydrogenase (LDH) from the myocardial cells in the culture supernatant at 6 hour after hypoxia and after glycine treatment were determined with ultraviolet spectrophotometer. The expression of the alpha1 subunits of glycine receptor (GlyRalpha1) in the myocardial cells was detected by immunofluorescent histochemistry. The changes in the intracellular calcium content and the membrane potential of the myocardial cells were determined by laser confocal microscopy.


RESULTS
The release of CK and LDH in the culture supernatant increased significantly at 6 h after hypoxia [(393.8 +/- 5.3), (1564 +/- 41) U/L] compared with those before hypoxia, while their levels were obviously decreased after glycine treatment [(56.3 +/- 2.7), (716 +/- 18) U/L, (P <0.01)] compared with those before glycine treatment. There was positive expression of GlyRalpha1 in myocardial cells before and after hypoxia. The average fluorescent intensity of intracellular calcium at 6 hours after hypoxia (139 +/- 29) was significantly higher than that before hypoxia (27 +/- 8, P < 0.01), while it was obviously lower (51 +/- 11) after glycine treatment compared with that at 6 hours after hypoxia,but it was evidently higher than that before hypoxia (P <0.01). The membrane potential 6 hours after hypoxia (62 +/- 9) was obviously lower than that before hypoxia (177 +/- 20, P < 0.01), but it was obviously higher after glycine treatment (123 +/- 16) than that at 6 hours after hypoxia (P < 0.01).


CONCLUSIONS
Glycine might be beneficial in the protection of myocardial cells against hypoxia. The underlying mechanism may involve attenuation of membrane potential depolarization after hypoxia by conjugation of glycine with its receptor, depleting in turn voltage-dependent calcium channel on the cellular membrane, preventing calcium overload due to influx of calcium ions after hypoxia.
Zhou
Jun-li
JL
Institute of Burn Research , Southwest Hospital , State Key Laboratory of Trauma, Burns and Combined Injury, The Third Military Medical University, Chongqing 400038, P. R. China.
Huang
Yue-sheng
YS
Dang
Yong-ming
YM
Zhang
Ji-ping
JP
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015687:Cell Hypoxia / Q000187:drug effects; D002478:Cells, Cultured; D003402:Creatine Kinase / Q000378:metabolism*; D005998:Glycine / Q000494:pharmacology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley
D007770:L-Lactate Dehydrogenase; D003402:Creatine Kinase; D002118:Calcium; D005998:Glycine