[Effects of LbGp on the intracellular free calcium concentration of cardiomyocytes induced by hypoxia and KCl].
OBJECTIVE
Hypoxia/KCl injury model in the cultured neonatal rat cardiomyocytes (CMs) was established to investigate the protective effect of Lycium barbanun Glycopeptide (LbGp) on calcium overload.


METHODS
Cultured neonatal rat CMs were divided into three groups, namely normal control, hypoxia groups and LbGp-treated group. CMs in LbGp-treated group and hypxia group were cultured in an incubator ventilated with 95% N2 and 5% CO2 with or without LbGP. CMs viability under hypoxia was measured by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide colorimetry (MTT). The intracellular free calcium concentration in cardiomyocytes was measured by laser confocal microscope with Fura-3/AM as a calcium indicator. The protective effects of LbGp on the CMs treated by KCl (60 mmol x L(-1)) was observed.


RESULTS
As compared with normal controls, the degree of MTT metabolism was significantly reduced (P < 0.01) in hypoxic group and slightly reduced in LbGp (P < 0.05). Hypoxia-induced enhancement of intracellular calcium ([Ca2+]i) was attenuated by LbGp significantly (P < 0.01). Moreover, KCl-induced enhancement of [Ca2+]i was also reduced by LbGp at the doses of 25, 50, 100 microg x mL(-1) in a concentration-dependent manner.


CONCLUSIONS
The result suggested that LbGp is able to increase the survival ratio and inhibit the enhancement of the intracellular free calcium concentration in cardiomyocytes induced by hypoxia and high potassium. One of the mechanisms is that LbGp acts on L-type calcium channels.
Xu
Shun-lin
SL
Department of Cardiology, The First Affiliated Hospital, Nanjing Medical University, Nanfang 210029, China. slheart@njmu.edu.cn
Huang
Jun
J
Tian
Geng-yuan
GY
D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism*; D015687:Cell Hypoxia; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006020:Glycopeptides / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D032305:Lycium / Q000737:chemistry; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D010946:Plants, Medicinal / Q000737:chemistry; D011189:Potassium Chloride; D051381:Rats; D017207:Rats, Sprague-Dawley
D006020:Glycopeptides; D011189:Potassium Chloride; D002118:Calcium