Smith K, Docherty J R
Department of Physiology, Royal College of Surgeons in Ireland, Dublin.
Eur J Pharmacol. 1992 Aug 25;219(2):203-10. doi: 10.1016/0014-2999(92)90297-h.
We have investigated the effects of antagonists at functional prejunctional alpha 2-adrenoceptors of rat was deferens and rat submandibular gland and compared potencies with affinities for the alpha 2A-, alpha 2B- and putative alpha 2D-ligand binding sites of human platelet, rat kidney, and rat submandibular gland, respectively. Prejunctional potency of antagonists was expressed as an EC30 (concentration producing a 30% increase in stimulation-evoked release of tritium in tissues pre-incubated with [3H]noradrenaline) in rat vas deferens and submandibular gland, and also as a pA2 (antagonist concentration producing a 2-fold shift in the inhibition by the alpha 2-adrenoceptor agonist xylazine of the electrically-evoked isometric twitch) in rat vas deferens. The functional prejunctional alpha 2-adrenoceptors of rat vas deferens and submandibular gland are alpha 2A-like since there was a good correlation between affinity for the alpha 2A-ligand binding site in human platelet and prejunctional potency in rat vas deferens (r = 0.90, n = 7, P less than 0.001), and submandibular gland (r = 0.84, n = 7, P less than 0.05). However, there was a better correlation between affinity for the alpha 2-ligand binding site of rat submandibular gland and prejunctional potency in rat vas deferens (r = 0.95, n = 7, P less than 0.001), and submandibular gland (r = 0.97, n = 7, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
我们研究了大鼠输精管和大鼠颌下腺功能性节前α2-肾上腺素能受体拮抗剂的作用，并分别将其效力与对人血小板、大鼠肾脏和大鼠颌下腺的α2A-、α2B-及假定的α2D-配体结合位点的亲和力进行比较。拮抗剂在大鼠输精管和颌下腺的节前效力，在输精管中用EC30表示（即与[3H]去甲肾上腺素预孵育的组织中，刺激诱发的氚释放增加30%时的浓度），在颌下腺中也用EC30表示；在输精管中还用pA2表示（即α2-肾上腺素能受体激动剂赛拉嗪对电诱发的等长收缩抑制作用产生2倍位移时的拮抗剂浓度）。大鼠输精管和颌下腺的功能性节前α2-肾上腺素能受体类似α2A，因为人血小板中对α2A-配体结合位点的亲和力与大鼠输精管（r = 0.90，n = 7，P < 0.001）和颌下腺（r = 0.84，n = 7，P < 0.05）的节前效力之间存在良好相关性。然而，大鼠颌下腺对α2-配体结合位点的亲和力与大鼠输精管（r = 0.95，n = 7，P < 0.001）和颌下腺（r = 0.97，n = 7，P < 0.001）的节前效力之间的相关性更好。（摘要截短于250字）
