Effect of tanshinone II A on the transforming growth factor beta1/Smads signal pathway in rats with hypertensive myocardial hypertrophy / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To investigate the molecular mechanism of tanshinone II A (TSN) for preventing left ventricular hypertrophy (LVH) by studying the expressions of angiotensin I type 1 receptor (AT1R), transforming growth factor beta1 (TGF-beta1) and intracellular signal protein gene (Smads gene) in the hypertrophic myocardium of hypertensive rat models induced by pressure over-loading.</p><p><b>METHODS</b>SD rat model of LVH was established by abdominal aorta constriction. The model animals were randomly divided into 4 groups 4 weeks after modeling, the untreated model control group (C1), the two tested groups (T1 and T2) treated respectively with high (20 mg/kg) and low (10 mg/kg) dose of TSN II A per day via intraperitoneal injection, and the positive control group (C2) treated with 10 mg/kg of Valsartan per day by gastric perfusion, with 8 animals in each group. Besides, 8 SD rats managed with sham operation were set up as the sham-operated control group (C3) After an 8-week treatment, the caudal arterial pressure, left ventricular mass index (LVMI), myocardial fiber dimension (MFD, by pathologic examination with HE staining) in rats were measured. Meanwhile, mRNA expression of AT1R, protein expression of TGF-beta1 and activity of Smad-3, 4, 7 in the ventricular tissue were detected by RT-PCR analysis and Western blotting respectively.</p><p><b>RESULTS</b>(1) Blood pressure in Group T1 and T2 was unchanged after treatment, which was significantly higher than that in Group C2 and C3 (P < 0.01, P < 0.05). (2) LVMI and MFD in Group T1, T2 and C2 were higher than that in Group C3 (P < 0.01), but remarkably lower than that in Group C1 (P < 0.01). (3) Levels of AT1R, TGF-beta1 and Smad-3 expression increased significantly in the model rats (P < 0.01), but they were down-regulated in Group T1 and C2, and the TGF-beta1 regulating effect in the C2 was more potent than that in Group T1 and T2 (P < 0.05). (4) Protein expression of Smad-7 was up-regulated in Group T1, T2 and C2 obviously (P < 0.01), and the effect in Group T1 was superior to that in C2 (P < 0.05).</p><p><b>CONCLUSION</b>The myocardial hypertrophy inhibition effect of TSN II A is a blood pressure independent process, and it may be related to the inhibition of AT1R mRNA expression and blocking of TGF beta1/Smads signal pathway.</p>

Effect of tashinone on nitric oxide synthase in hypertrophic cardiomyocyte of rats suffered abdominal aorta constriction / 中国中药杂志

<p><b>OBJECTIVE</b>To explore the molecular biological mechanism for tanshinone II A reversing left ventricular hypertrophy, it would be studying the effect of tashinone on the endothelial nitric oxide synthase (eNOS) and protein kinase C (PKC) in the hypertrophic cadiocyte of rats suffered abdominal aorta constriction.</p><p><b>METHOD</b>SD rats were operated with abdominal aorta constriction and 8 rats were done with sham surgery. After 4 weeks, all rats were divided into 4 groups: myocardial hypertrophy group, low dose tanshinone II A group (10 mg x kg(-1) x d(-1)), high dose tanshinone II A group (20 mg x kg(-1) x d(-1)) and valsartan group (10 mg x kg(-1) d(-1) intragastric administration). 8 weeks later, the rats were used to measure 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 the nitric oxide content by nitrate reductase, to detect the genic expression of eNOS by RT-PCR and to detect the activity of protein kinase C (PKC) by Western blotting.</p><p><b>RESULT</b>1) The blood pressure in group myocardial hypertrophy [(186 +/- 13) mmHg] and tansginone II A [low and high dose (188 +/- 11,187 +/- 14) mmHg] was obviously higher than that in group sham surgery and valsartan group [vs (117 +/- 8, 136 +/- 15) mmHg, P < 0.01]. But there was no difference between group myocardial hypertrophy and group tanshinone II A (low and high dose). 2) The LVMI and MFD were obviously higher in group tanshinone II A low and high dose) and group valsartan than those in group sham surgery (P < 0.05), and lower than those in group myocardial hypertrophy (P < 0.01). 3) The NO level was obviously higher in group tanshinone II A (low and high dose) and group valsartan than that in group myocardial hypertrophy (12.78 +/- 1.66, 11.95 +/- 1.39, 12.26 +/- 2.08 vs 5.83 +/- 1.06) micromol x L(-1), (P < 0.01 ), and lower than that in group sham surgery (vs 19.35 +/- 1.47) micromol x L(-1), (P < 0.05). 4) The expressive level of eNOS mRNA and protein in myocardial hypertrophy group was less than that in other groups (P < 0.01). And valsartan group was less than tanshinone II A groups and sham surgery group (P < 0.05), but there were no difference among the two tanshinone II A groups and sham surgery group. 5) The level of PKC protein in group myocardial hypertrophy was obviously higher than that in all the other groups (1.291 +/- 0.117 vs 0.563 +/- 0.094, 0.605 +/- 0.051, 0.519 +/- 0.062, 0.827 +/- 0.086, P < 0.01), and the level in group valsartan was higher than that in group sham operation and group tanshinone II A (low and high dose).</p><p><b>CONCLUSION</b>NO/NOS system in local myocardium has close relationship with the pathological process for myocardial hypertrophy. Tanshinone II A can produce the pharmacological action to reverse myocardial hypertrophy by inhibiting the activity of PKC and promoting the genic expression of eNOS in local myocardium and the production of endogenous NO.</p>