Effect of calcium-sensing receptor in cardiac hypertrophy induced by angiotensin II in cultured neonatal rat cardiomyocytes

Abstract

Objective To explore the roles and possible mechanism of calcium-sensing receptor(CaSR) in cell cardiac hypertrophy model using angiotensin Ⅱ (Ang Ⅱ ).Methods The cultured neonatal rat ventricular myocytes were treated with Ang Ⅱ as cell cardiac hypertrophy model.Hypertrophic neonatal rat cardiomyocytes were treated with GdCl3(a specific agonist of CaSR) and/or with Ro318220(a specific inhibitor of PKC pathway).To evaluate the status of cardiac hypertrophy,cell diameter was observed by HE dyeing,and protein content was determined through coomassie brilliant blue protein kit.The intracellular calcium concentration( [ Ca2+]i) was determined by laser scanning confocal microscope.The protein expression of CaSR and PKC pathway were analyzed using Western blotting.Results ①Compared to the control group(0.1263 ± 0.0443),the protein expression of CaSR was increased in Ang Ⅱ group and in GdCl3 group(0.1963 ± 0.0375,0.2778 ± 0.0564,all P＜ 0.05).Moreover,compared with Ang Ⅱ alone,the increase was significant in GdCl3 group(P ＜ 0.05).②Compared to control group(222.70 ± 22.09),AngⅡ group(392.16 ± 36.85) remarkably increased [Ca2+]i(P＜ 0.05),and this increase of [Ca2+]i was further enhanced in GdCl3 group (502.60 ± 44.21) versus Ang Ⅱ group (P ＜ 0.05).③Compared to control group,Ang Ⅱ could induce cardiomyocyte hypertrophy,and GdCl3 enhanced the effect.Moreover,this enhancement was attenuated by Ro318220.④Compared to control group(0.27 ± 0.07,0.69 ± 0.06,0.87 ± 0.04),the protein expression of PKCα,PKCe and PKCδ was increased in Ang Ⅱ group(0.60 ± 0.16,1.02 ± 0.13,1.20 ± 0.18,all P＜ 0.05) and the protein expression of PKCα,PKCe was increased in GdCl3 group(0.82 ± 0.16,1.34 ± 0.12,all P ＜ 0.05).Moreover,compared with Ang Ⅱ group,the protein expression of PKCα,PKCe was obviously increased in GdCl3 group (all P ＜ 0.05);compared with GdCl3 group,the protein expression of PKCα,PKCe(0.41 ± 0.10,0.85 ± 0.14) was obviously decreased in Ro318220 group(all P ＜ 0.05).Conclusions CaSR is involved in cardiac hypertrophy induced by Ang Ⅱ through PKC pathway in cultured neonatal rat cardiomyocytes. Key words: Receptors, calcium-sensing; Protein kinase C; Angiotensin Ⅱ ; Cardiac hypertrophy