Tanshinone II-A attenuates cardiac fibrosis and modulates collagen metabolism in rats with renovascular hypertension

The adaptive changes that develop in the pressure-overloaded left ventricular myocardium include cardiac hypertrophy and interstitial fibrosis. The objectives of the present study were to evaluate the effects of Tanshinone II-A, a bioactive diterpene quinone isolated from Danshen, on cardiac fibrosis and collagen metabolism in rats with renovascular hypertension. Male Sprague-Dawley rats were subjected to two-kidney two-clip (2K2C) or sham operation (sham) and treated with Valsartan (Val, 26.7 mg/kg/d), Tanshinone II-A (Tsn, 70, 35 mg/kg/d) or vehicle. Six weeks later, systolic blood pressure (BP), LV weight, collagen abundance, cardiac function parameters, hydroxyproline content and mRNA levels of matrix metalloproteinase (MMP)-2, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 were evaluated. Both high-dose (Tsn-H, 70 mg/kg/d) and low-dose (Tsn-L, 35 mg/kg/d) of Tsn failed to attenuate 2K2C-induced BP elevation but significantly attenuated the attendant interstitial fibrosis. Val suppressed elevations of BP and left ventricular systolic pressure (LVSP) in 2K2C rats. Val and Tsn-H exerted comparable suppressive effects on the gene expression of MMP-9 and TIMP-1, while Val decreased the MMP-2 mRNA level without affecting the transcript levels of TIMP-2. Both Val and Tsn-H attenuated cardiac dysfunction, while Tsn-L showed slight improvement. These data demonstrate for the first time, that Tsn prevented cardiac fibrosis and improved cardiac function in a rat model of renovascular hypertensive independent of hypotensive effect. Tsn conferred its beneficial effects on the collagen metabolism probably through its regulation of transcript levels of the MMPs/TIMPs balance.