Decreased vasodilatory effect of Tanshinone ⅡA Sodium Sulfonate on mesenteric artery in hypertension.

Tanshinone ⅡA Sodium Sulfonate (DS-201), a derivative of traditional Chinese medicinal herb Danshen, has been clinically used for various cardiovascular diseases. Previous studies showed that DS-201 induced vascular relaxation partly due to the activation of the large conductance Ca2+-activated potassium (BKCa) channels. However, the efficacy of DS-201 on the resistant vessels in hypertension remains unknown. Mesentery arteries obtained from spontaneously hypertensive rats (SHR) and hypertension patients were used in this study. The endothelium-denuded mesenteric arteries were prepared to measure the artery tension and evaluate the vasodilatory effect of DS-201. The results showed that DS-201 had a vasodilatory effect on the mesenteric artery rings pre-contracted with either phenylephrine (PE) or thromboxane mimetic U46619 in a concentration-dependent manner. However, the vasodilatory effect of DS-201 significantly decreased in hypertension than in control arteries due to a decrease in protein level of BKCa β1subunit. A BKCa channel blocker IbTX (200 nM) significantly inhibited the relaxant effect of DS-201 on non-hypertensive arteries, whereas the BKCa channel specific agonist NS1619 rescued the vasodilating effects of DS-201 on hypertensive vessels. These results indicate that the vasodilating effect of DS-201 is BKCa-dependent. This study demonstrated that DS-201 alone may not be effective for treating hypertension, but it may be considered as therapy combined with BKCa-agonists or methods rescuing BKCa functions.