Ruffolo R R, Zeid R L
Eur J Pharmacol. 1985 May 8;111(2):267-71. doi: 10.1016/0014-2999(85)90767-8.
The relationship between alpha 2-adrenoceptor occupancy and contractile response for B-HT 933 was investigated in canine saphenous vein. B-HT 933 produced a concentration-dependent, alpha 2-adrenoceptor mediated contractile response in canine saphenous vein with an ED50 of 0.65 microM. The dissociation constant (KA) of B-HT 933 was calculated to be 5 microM. The relationship between alpha 2-adrenoceptor occupancy and contractile response for B-HT 933 in canine saphenous vein was hyperbolic, typical of full agonists or agonists with high intrinsic efficacies. B-HT 933 produced a half-maximal response in canine saphenous vein at only 11% alpha 2-adrenoceptor occupancy, with a maximal response being obtained with 40-60% alpha 2-adrenoceptor occupancy. We conclude that the selective alpha 2-adrenoceptor agonist, B-HT 933, has high efficacy at alpha 2-adrenoceptors, such that a significant alpha 2-adrenoceptor reserve, or spare alpha 2-adrenoceptors, exists for this compound in canine saphenous vein.
在犬隐静脉中研究了α2 -肾上腺素能受体占有率与B - HT 933收缩反应之间的关系。B - HT 933在犬隐静脉中产生浓度依赖性的、α2 -肾上腺素能受体介导的收缩反应，ED50为0.65微摩尔。计算得出B - HT 933的解离常数（KA）为5微摩尔。在犬隐静脉中，α2 -肾上腺素能受体占有率与B - HT 933收缩反应之间的关系呈双曲线，这是完全激动剂或具有高内在活性的激动剂的典型特征。B - HT 933在犬隐静脉中仅在11%的α2 -肾上腺素能受体占有率时产生半数最大反应，在40 - 60%的α2 -肾上腺素能受体占有率时获得最大反应。我们得出结论，选择性α2 -肾上腺素能受体激动剂B - HT 933在α2 -肾上腺素能受体上具有高效能，以至于在犬隐静脉中该化合物存在显著的α2 -肾上腺素能受体储备或备用α2 -肾上腺素能受体。
