AIM: To elucidate the role of NO in the effect of tetramethylpyrazine (TMP) on vasomotion of arterioles induced by noradrenalin(NA).METHODS: Albino rabbits were anesthetized,respiration were maintained,the arterial pressure were measured with a pressure transducer attached to a polyethylene canula in the left common carotid artery,the intestinal loop was mounted on the stage of an inverted microscope and bathed in balanced solution.The inside diameter of the arterial was manually measured on a TV monitor using the TV camera mounted on the microscope.RESULTS: Topical applicated NA to measured field inducd spontaneous vasomotion which has frequency and amplitude.TMP inhibited vasomotion in vasodilation. Treatment with L-NMMA did not affect the effect of TMP.CONCLUSION: L-NMMA can not inhibit action of TMP on vasomotion,TMP may act on smooth muscle directly, not through endogenous NO.

Objective:The aim of this study was to observe the role of NO in the action of tetramethylpyrazine (TMP) on arterioles vasomotion induced by noradrenaline (NA), in order to make further understand of vasodilation mechanism of TMP.Methods: Albino rabbits weighting 2.0 ～ 2.5 kg were anesthetized. They were ventilated with room air via tracheotomy tube. The arterial pressure was monitored with a pressure transducer attached to a polyethylene canula in the right common carotid artery by four channel polygraph, the intestinal loop was mounted on the stage of an inverted microscope and bathed in balanced Kreb Ringer solution maintained at 37.5 ?C . The inside diameter of arterioles were measured manully on a TV monitor using a TV camera mounted on the microscope. Observe the changes of BP、 microcirculation and filtration of true capillary after injection of TMP 8mg/kg、 N G monomethyl L arginine( L NMMA) 10mg via a cannula in the left carotid artery after topical application of NA(0.8?g) conducted in the measured field. Results:TMP can inhibit spontaneous vasomotion in vasodilation; L NMMA can inhibit it in vasoconstriction stage. L NMMA have no effect on the action of TMP. Conclusions: Endogenous NO has no role in TMP's vasodilation.