Ruffolo R R, Patil P N
Blood Vessels. 1979;16(3):135-43. doi: 10.1159/000158200.
The rates of onset and offset of alpha-adrenoreceptor blockade by phentolamine (5 X 10(-7) M) have been studied on the normal and denervated rabbit aorta and rat vas deferens. Removal of the adventitia with its accompanying sympathetic nerve component results in an approximately threefold increase in the rate of onset of alpha-adrenoreceptor blockade by phentolamine in the rabbit aorta. The rate of offset of blockade by the antagonist on the aorta is likewise faster after the adventitia has been removed (approximately threefold faster for loss of 90% of the antagonist from the region of the receptors). This effect is not likely to be attributed to the absence of sympathetic nerve terminals since surgical denervation of the rat vas deferens has no effect on the kinetics of receptor blockade in this densely innervated organ. These data suggest that the adventitia of the rabbit aorta may serve as a diffusion barrier which limits the antagonist's access to, and efflux from, the region of the receptors. The dissociation constant of phentolamine (calculated from the equilibrium dose ratio) on the alpha-adrenoreceptor is unaltered by denervation in either tissue and is identical in both tissues. It is suggested that alpha-adrenoreceptors in the rabbit aorta and rat vas deferens are of a single type and are not significantly affected, with respect to antagonist affinity, by denervation.
已在正常和去神经的兔主动脉及大鼠输精管上研究了酚妥拉明（5×10⁻⁷ M）对α-肾上腺素能受体的阻断起效和失效速率。去除含有交感神经成分的外膜后，酚妥拉明对兔主动脉α-肾上腺素能受体的阻断起效速率增加约三倍。在外膜去除后，拮抗剂对主动脉的阻断失效速率同样更快（从受体区域失去90%拮抗剂的速率快约三倍）。这种效应不太可能归因于交感神经末梢的缺失，因为大鼠输精管的手术去神经对这个神经密集分布器官的受体阻断动力学没有影响。这些数据表明，兔主动脉的外膜可能作为一个扩散屏障，限制拮抗剂进入和离开受体区域。酚妥拉明在α-肾上腺素能受体上的解离常数（根据平衡剂量比计算）在两种组织中均不受去神经影响，且在两种组织中相同。提示兔主动脉和大鼠输精管中的α-肾上腺素能受体属于同一类型，就拮抗剂亲和力而言，不受去神经的显著影响。
