Vanhoutte P M, Shepherd J T
Fed Proc. 1985 Feb;44(2):337-40.
A comparison has been made of the factors concerned with the response of canine and human saphenous veins to adrenergic stimulation. Both vessels have prejunctional muscarinic and beta-adrenergic receptors. When activated by appropriate agonists these receptors decrease and increase the output, respectively, of norepinephrine from the nerve endings. Both vessels have postjunctional alpha 1 and alpha 2 adrenoceptors and postjunctional beta adrenoceptors. Activation of the former two receptors leads to contraction of the smooth muscle, and of the latter to relaxation. There are, however, qualitative differences. In the human veins the responsiveness of the prejunctional beta adrenoceptors exceeds that of the postjunctional, whereas the reverse is true in the dog. As a consequence, in the human vein beta-adrenergic agonists augment, and in the canine veins they depress, the contractile response to sympathetic nerve stimulation.
对犬类和人类隐静脉对肾上腺素能刺激反应相关的因素进行了比较。两种血管都有节前毒蕈碱和β-肾上腺素能受体。当被适当的激动剂激活时，这些受体分别减少和增加神经末梢去甲肾上腺素的释放量。两种血管都有节后α1和α2肾上腺素能受体以及节后β肾上腺素能受体。激活前两种受体导致平滑肌收缩，而激活后一种受体则导致平滑肌舒张。然而，存在质的差异。在人类静脉中，节前β肾上腺素能受体的反应性超过节后受体，而在犬类中则相反。因此，β-肾上腺素能激动剂在人类静脉中增强，而在犬类静脉中则抑制对交感神经刺激的收缩反应。
