Role of calcineurin signal transduction pathway in the inhibition of cardiac hypertrophy by L-arginine in vivo and in vitro / 中国药理学通报

ABSTRACT

Aim To study the role of calcineurin signal transduction pathway in the anti-hypertrophic effect of L-arginine in vivo and in vitro.Methods The hypertrophic effects was assayed by calculating the right ventricular hypertrophy index(RVHI=right ventricle weight/left ventricle and septum weight),and atrial natriuretic peptide(ANP)mRNA expression in rat right ventricle hypertrophy model induced by monocrotaline(MCT) or by measuring the cell diameter,protein content,and ANP mRNA expression in hypertrophic cardiomyocyte induced by prostaglandin F2?(PGF2?).For mechanism studies,the intracellular free calcium concentration([Ca2+]i) in cultured cardiomyocytes was measured by using Fura 2/AM as a fluorescent indicator.ANP and CaN mRNA expressions,and expressions of CaN and its downstream effectors,NFAT3 and GATA4 proteins were assayed by RT-PCR and Western blot,respectively,in vivo and in vitro.Results In MCT-hypertrophic model,prevention-and treatment-administration of L-arginine,a nitric oxide(NO) precursor,200 mg?kg-1?d-1,could obviously inhibit the elevated RVHI and ANP mRNA expression;similar to that found in vivo.Addition of L-arginine 1 mmol?L-1 could markedly inhibit the increased cell diameter,protein content and the expression of ANP mRNA in the hypertrophic cardiomyocyte induced by PGF2? 100 nmol?L-1,and it could also decrease the elevated [Ca2+]i in vitro;notably,the above dose or concentration of L-arginine could blunt the elevated expressions of calcineurin mRNA and the calcineurin-,NFAT3-,GATA4-proteins induced by MCT or by PGF2?.These effects of L-arginine were blocked by NG-nitro-L-arginine-methyl ester,a NO synthase inhibitor,in vivo and in vitro.Conclusion These results suggest that calcineurin signal transduction pathway may play an important role in the NO-induced inhibition of cardiac hypertrophy.The anti-hypertrophic effects of L-arginine may involve the decrease of [Ca2+]i,and then inhibit the activated calcineurin pathway,through the release of NO.