Abstract:Objective： To explore the effect and mechanism of kansui root on microcirculation of pancreatic tissues in severe acute pancreatitis(SAP) rats. Methods：SD rats were randomly divided into sham group (S group), SAP group and kansui root therapy group (K group). 40 rats in each group. Serum amylase, and thromboxame-B2(TXB2) ,6-Keto-F1α(6-Keto PGF1α)levels and expressions of cyclooxygenase-2(COX-2)mRNA and protein in pancreatic tissue, microscopy and election microscopy of pancreas,mortality within 72 hour after operation in each group were tested at 2h,6h,12h,and 24h after operation. Results：(1)The TXB2,6-keto PGF1α levels and the ratio of TXB2/6-Keto-PGF1α(T/P) in SAP group were all obviously higher than those in S group (P<0.01); the TXB2 levels and the ratios of T/P in K group at 6h,12h,and 24h were significantly lower than those in SAP group(P<0.01),but were significantly higher than that in S group (P<0.01).(2)Expression of COX-2 mRNA and protein were rare in S group, but expression in SAP group was significant. In K group expression of COX-2 mRNA at 6h and 12h and expression of COX-2 protein at 6h,12h,and 24h were significantly lower than those in SAP group(P<0.01 or P<0.05). (3)Correlation analysis :the ratio of T/P was significantly correlated to COX-2 protein expression in pancreatic tissue(P<0.01).(4)Microscopy and electron microscopy of pancreas: histologic structures of pancreas were normal in S group;hemorrhage, necrosis and abundant thrombosis in microvessels were observed in pancreatic tissue in SAP group; in K group the pancreatic injury was milder, and thrombosis in microvessels was decreased than that in SAP group.(5)Mortality within 72 hours in S group was 0%,in K group was 12.5%,both were significantly lower than that in SAP group (62.5%)(P<0.05). Conclusions：There was high expression of COX-2 and imbalance between TXA2 and PGI2 in SAP rats. Kansui root may reduce the expression of COX-2 and by correction of the imbalance between TXA2 and PGI2 which can improve the microcirculation of pancreas. This may be one of the mechanisms of the effect of kansui root in treating SAP in rats.