AIM To elucidate the mechanism of
Polydatins effects on small blood vessels. METHODS The changes of cytosolic free calcium
concentration
i, intracellular pH and cell membrane potential (MP) kinetically were determined in a single vascular smooth muscle cell (VSMC) isolated immediately with 20～30 min pronase E (1 g·L -1 )digestion from mesenteric arterioles of rats. Animals were divided into two groups: control group and shock group. The hemorrhagic shock model was prepared by withdrawal of blood from femoral arteries and maintained mean arterial pressure at 5 32 kPa for 90 min. VSMC were labeled with specific fluorescent probe of Fluo 3 AM, Snarf and DiBAC 4 respectively to measure i, pH and MP with a adherent cell analysis and sorting system(ACAS 570). RESULTS It was found that polydatin(0 4 mmol·L -1 ) caused a significant decrease of the VSMC i in shock group (78 4%±5 6% vs baseline), but had a increase of the VSMC i in control group (117 5%±6 3% vs baseline). The pH changes after adding polydatin was similar to that of i. When pretreated with verapamil (50 μmol·L -1 ) 10 min before giving polydatin, the VSMC i was decreased remarkably both in control and shock group. It was also found that polydatin might cause the VSMC MP elevated (depolarization) about 15%±2 1% in control group and 23%±3 0% in shock group respectively. When pretreated with verapamil and EGTA (2 mmol·L -1 ), the MP was still elevated 28%±5 7% vs baseline; But when pretreated with tetrodotoxin (1 μmol·L -1 , a kind of sodium channel blocker), the depolarization of polydatin was inhibited completely. CONCLUSION These data suggested that polydatin had up and down regulation effects on i and pH of VSMC, and polydatin also induce the entry of extracellular sodium ion to make the cell depolarization.