Effect of tanshinoneIIA on angiotensin receptor and free calcium ion in hypertrophic myocardium of rats due to abdominal aorta constriction

Objective To explore the molecular biological mechanism about tanshinoneⅡA reversing left ventricular hypertrophy,it would be studied how tanshinoneⅡA gave an impact to angiotensin receptor and free calcium ion in hypertrophic myocardium of rats due to abdominal aorta constriction.Methods SD rats were operated with abdominal aorta constriction and 8 rats were done with artificial surgery.After 4weeks,all rats were divided into 4 groups:myocardial hypertrophy group,Low dose tanshinone ⅡA group(10 mg·kg-1·d-1),high dose tanshinone ⅡA group(20 mg·kg-1·d-1) and Valsartan group(10 mg·kg-1·d-1 intragastric administration).8 weeks later,measuring the left ventricular mass index(LVMI) with the tissue of left ventricle and myocardial fiber dimension(MFD) by pathological section and HE stain.To detect mRNA and protein's expression of AT1 receptors in left ventricular tissues of all groups by RT-PCR and Western blotting.Ca2+i was observed with laser-scanning confocal microscope.Results ① The blood pressure in group myocardial hypertrophy(186±13)mm Hg and tansginone ⅡA low and high dose,(188±11,187±14)mm Hg was obviously higher than that in group artificial surgery and Valsartan group vs(117±8,136±15)mm Hg,P0.01.But there was no difference between group myocardial hypertrophy and group tanshinoneⅡA(low and high dose)(P0.05).② The LVMI and MFD were obviously higher in group tanshinoneⅡA(low and high dose) and group Valsartan than that in group artificial surgery(P0.05),and lower than group myocardial hypertrophy(P0.01).③ The mRNA and protein's expression of AT1 receptor in myocardial hypertrophy group were obviously more than that in other groups(P0.01);there were no difference within two tanshinoneⅡA groups(P0.05),but tanshinoneⅡA groups was higher than valsartan group(P0.05).The genic expression in these three groups did not recover to normal lever(artificial surgery group)(P0.05).④The concentration of calcium ion in myocardial hypertrophy group was highest(vs other groups,P0.01);and that in the two tanshinoneⅡA groups and artificial surgery group had not statistically different(P0.05),but they were lower than that in valsartan group(P0.05).Conclusion TanshinoneⅡA and Valsartan both could resist the myocardial hypertrophy by downregulating the genic expression of AT1 receptor and blocking the inflow of calcium ion in cadiocyte.The effect of tanshinoneⅡA on myocardial hypertrophy was not dependent on blood pressure.