RESUMEN
Objective Calcium-sensing receptor(CaSR)belongs to the family C of G-protein coupled receptors.This study was carried out to observe the influence and mechanism of CaSR on anoxia/reoxygenation(A/R)-induced cardiomyocytes apoptosis.Methods The model of A/R injury was established through anoxia for 2 hours and reoxygenation for 24 hours in cultured cardiomyocytes of neonatal rats.Cardiomyocytes were randomly divided into three groups:control group,A/R group and GdCl3 group(300μmol/L GdCl3 was added to the culture medium at the beginning of reoxygenation).Apoptosis of cardiomyocytes was assessed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling(TUNEL).The expression of CaSR,cysteine-requiring aspartate protease(caspase)-3,9 and cytochrom c (Cytc)were analyzed by Western blot.Results The TUNEL showed that cardiomyocytes apoptosis was 17%±3% in A/R group,and was higher than that in the control group.At the same time,expression of CaSR in A/R group was markedly increased in response to control group.Compared with A/R group,GdCl3,a specific activator of CaSR,further enhanced cardiomyocytes apoptosis to (28±4)% and decreased the ability of cardiomyocytes to (51.2±6.8)%,along with an increment in CaSR,caspase-3,caspase-9 and Cytc expressions.Conclusion CaSR is involved in anoxia/reoxygenation-induced apoptosis of neonatal rat cardiomyocytes through Cytc-caspase-3 pathway.