Aim To study the effect of ginsenoside Rg1(Rg1)on cardio myocyte hypertrophy induced by prostaglandin F2?(PGF2?),and to probe primarily into its mechanism.Methods The cultured neonatal rat cardiomyocyte hypertrophic response and the antihypertrophic effects of Rg1 were observed by measuring the cell diameter,protein content and the expression of atrial natriuretic factor(ANF) mRNA,which was assayed by real-time PCR.For mechanism studies,the intracellular free calcium concentration(i) in cultured cardiomyocytes was measured by using Fura-2/AM as a fluorescent indicator,nitric oxide(NO) metabolite level in the culture medium was tested by using Nitric Oxide Synthase Detection Kit.Results PGF2? 0.1 ?mol?L-1 caused the increases in the cardiomyocyte cell diameter,protein content and the expression of ANF mRNA.It could increase the i in cultured cardiomyocytes.Rg1 15.6、31.2、62.4 ?mol?L-1 could concentration-dependently inhibit the cardiomyocyte hypertrophy induced by PGF2?,and the cell diameter of cardiomyocyte treated by PGF2? was decreased by 18.4%、32.7%、43.8%(P