ABSTRACT
Objective To study the intervention effect of tanshinone on electrophysiological abnormality of hypertrophic cardicoyte in order to illuminate the underlying mechanism of tanshinone in preventing the arrhythmia induced by myocardial hypertrophy. Method Twenty-week-rid SD rats (200～250 g) were divided into 4 groups (8 in each group) randomly. Of 4 groups, rats of three groups were operated on by a procedure of 'one kidney one clamp' to make renal artery constriction. The rest group served as sham operation group (control group). When the blood pressure increased,rats of operation groups were divided into tanshinone group, captopril group and hyper-trophic group. The effects of tanshinoe and captopril were observed and compared on the action potential duration (APD),L-type calcium current (ICa, L) and transient outward potassium current (Ito) density in cellular membrane of hypertrophic myocardium by using patch clamp and intra-cellular calcium survey technique. Results The blood pressure in operation groups was obviously higher than that in sham-operation group (P<0.01), but there was no difference between operation groups (P>0.05). The ratio of ventricle weight to body weight (VW/BW) was much higher in hypertrophic group than in control group (P<0.01), and it significantly decreased after interven-tion with tanshinone or captopril (P<0.01). Compared with hypertrophic group, tanshinone markedly shortened the prolongation of action potential duration (P<0.01), decreased membrane capacity and peak amplitude of ICa,L(P<0.01), but had no effect on the density of ICa,L. Tanshinone also significantly increased Ito current density and peak amplitude, which were completely different from hypertrophic group (P<0.05). There were similar results foundin captopril intervention. Conclusions Tanshinone could reduce calcium influx and resume the activity of ho ion channels, and thus shorten the first phase and the plateau phase of repolarization and decrease the prolongation of APD in hypertrophic cadiocyte. So tanshinone can prevent the onset of arrhythmia attributed to the myocardial hypertrophy.