神经肽Y对离体兔脑血管的作用及其内皮依赖关系

神经肽Y对离体兔脑基底动脉的作用表现在:(1)直接收缩;(2)增强组胺的收缩效应;(3)抑制乙酰胆碱和腺苷的舒张效应。作用(1)和(3)不依赖于血管内皮的存在,而作用(2)依赖血管内皮,其机理可能是由于神经肽Y对血管内皮舒张因子(EDRF)的释放或作用具有抑制性影响。

Effects of neuropeptide Y on isolated rabbit basilar artery and its dependence on the endothelium

The effects of neuropeptide Y(NPY)on vascular constriction and relaxation were studied in isolated ring preparations of the rabbit basilar arteries,in which the endothelium was either intact or removed.The results showed:(1)NPY caused concentration-dependent vasoconstrictions that were the same as in the endothelium-intact and-denuded preparations.(2)In the endothelium-intact preparations.30 nmol/L NPY caused a significant shift to the left in the concentration-response curves(CRCs)for histamine.In the endothelium-removed preparations,the CRCs for histamine were shifted to the left significantly as compared with those in the endothelium-intact preparations.In the presence of 30 nmol/L NPY,the CRCs were not further shifted.In the endothelium-intact preparations,the histamine CRCs were shifted to the right significantly in the presence of 10μmol/L acetylcholine(ACh).In the presence of 30nmol/L NPY,together with 10μmol/L ACh,the curves were not shifted.(3)In thepresence of NPY,the CRCs for adenosine were shifted to the right significantly either in the endothelium-intact preparations or in the endothelium-removed preparations.But in the former preparations,30 nmol/L NPY also caused a significant shift of the ACh CRCs to the right.There was no response to ACh in the endothelium-removed preparations.We conclude that in the isolated rabbit basilar arteries,NPY can(1)cause contraction directly;(2)potentiate the responses to vasoconstrictors and(3)inhibit the responses to vasodilators.The first and the third effects are not dependent on the endothelium,while the second one is dependent on it.The data suggest that NPY potentiates the effect of vasoconstrictors by the mechanism of the inhibition of endothelium-derived relaxing factors.