Abstract: Objective To compare the effects of nitroglycerine (NTG)， Verapamil(VP), papaverine(PA) and the mixed solution of Verapamil and nitroglycerine (VG) on relaxing function of human radial arteries. Methods The radial arteries of thirty patients were used during the operation of coronary artery bypass grafting (CABG). A short segment (1.0-1.5cm) of radial arteris were taken from the distal end of radial arteries of each patient and were cut into vascular rings, which were mounted in the organ bath chamber and then subject to a series of tests for vascular smooth muscle viability and endothelial integrity. The effects of five storage solutions on the relaxing function were evaluated by “OrganBath” technique. The five solutions included: (1) Ringer’ s solution (control group); (2) VP solution (VP group); (3) NTG solution (NTG group); (4) PA solution (PA group); (5) VG solution (VG group). First, challenged with phenylephrine (10-5mol/L), vasorelaxant effect of these drugs (effect onset and efficacy) was observed at different time point and resting tension was recorded. Second, after 30min preincubation with either verapamil, papaverine, phenoxybenzamine or VG mixture, potassium chloride (final concentration of 60mmol/L) was added in the organ bath chamber and then vasoconstriction was observed subsequently. Finally, after 30min pretreatment of different antispasmodic agent in the same way as described above, the vascular rings were mounted in organ bath chamber and challenged with phenylephrine(10-5mol/L). Vascular spasticity and vosospasm duration were observed at different time point which might provide guidance for optimal timing of clinical application. Results The radial arteries in VG, VP, NTG and PA solutions were relaxed in 11 min after vasospasm and there was no difference between them (Pgt;0.05). But during the initial three minutes，the relaxation effect of VG and NTG was significantly better than other two groups. Relaxation curve showed that the ability of vasodilatation of VG, NTG, VP and PA decreased in order. In the experiment about antivasospasm pretreatment of radial arteries, there was no difference between VG and VP group (Pgt;0.05 ), whose effects were better than NTG and PA group(Plt;0.05 ). After cold storage for 24h, VG and VP still could prevent vasospasm. But NTG and PA hardly had any function and there was no difference compared with the control group (Pgt;0.05 ). Conclusion Although in the final all these drugs could prevent and relieve vasospasm of radial arteries in the different level, it appeared that a combination of verapamil and nitroglycenn is more fit for treating radial artery during CABG operation than other drugs.
OBJECTIVE: To explore the mechanism of microvascular spasm after limb ischemia-reperfusion. METHODS: The rabbit hindlimb normothermic tourniquet ischemia model was employed. The tendon on the dorsum of the foot was exposed for observation of microvessels. The responses of arterioles on tendon surface to topical application of 10(-6) mol/L noradrenaline (NE) (a vasoconstrictor), 10(-6) mol/l acetylcholine(Ach) (an endothelium-dependent vasodilator) and 10(-4) mol/L nitroglycerin(NTG) (an endothelium-independent vasodilator) were observed at the period of ischemia and following 30 minutes of reperfusion after 2 hours and 5 hours of ischemia by use of intravital microscopy. RESULTS: No significant changes in the responses of arterioles to NE, Ach and NTG were noted following 30 minutes of reperfusion after 2 hours of ischemia compared with pre-ischemia. The constrictor responses of arterioles to NE were still not significantly altered following 30 minutes of reperfusion after 5 hours of ischemia, however, the dilation responses to Ach and NTG were significantly decreased (to Ach P lt; 0.01; to NTG, P lt; 0.05). CONCLUSION: Reperfusion after 5 hours of ischemia significantly impairs both the endothelium-dependent and endothelium-independent vasodilation, meanwhile preserves constrictor responses to NE, these may contribute to the genesis of the vasospasm in ischemia reperfusion.