Vasoconstrictive Effect of Xinmailong Injection in Rat Aorta

Background: Cockroach has been traditionally utilized in China for the therapy of cardiovascular disorders, such as heart failure.The present study was aimed to assess the vasoconstrictive effect of Xinmailong Injection (XML), a bioactive composite from American cockroach. Methodology:The isometric tensions of rat aortic rings were measured after acutely treated with XML.Meanwhile, the systemic blood pressures (SBPs) were recorded and the levels of the endothelium-derived cytokines in blood samples were detected after rats were administered with XML for 3 days.Protein expression for the L-type Ca 2+ channels (Ca v1.2 ) was also determined in rat thoracic aorta.Results: XML induced vasoconstrictions in rat aortic rings with or without endothelium.In addition, the vasoconstrictions due to the extracellular Ca 2+ influx and the intracellular Ca 2+ release were also elevated by XML.After treatment with XML for 3 days, the level of prostacyclin (PGI 2 ) was markedly increased whereas the levels of nitric oxide (NO) and endothelin-1 (ET-1) were not significantly changed in rats.Furthermore, expression of the Ca v1.2 protein was significantly enhanced in aorta but the SBPs of rats were not influenced. Conclusion:XML plays an important role in regulating vascular tone.The increases of the extracellular Ca 2+ influx and the intracellular Ca 2+ release may contribute to the vasoconstriction induced by XML.Our findings pave the ways to the better understandings of the therapeutic effects of XML on cardiovascular system.