Ioudina M V, Dyer D C
Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
J Vet Pharmacol Ther. 2002 Oct;25(5):363-9. doi: 10.1046/j.1365-2885.2002.00414.x.
Ioudina, M. V., Dyer, D. C. Pharmacological characterization of alpha1-adrenoceptor subtypes in the bovine tail artery. J. vet. Pharmacol. Therap. 25, 363-369. The purpose of this study was to identify the alpha1-adrenoreceptor subtypes present in the bovine tail artery which mediate contractions to adrenergic agonists. A61603, an alpha1A-selective agonist, was more potent compared with norepinephrine and phenylephrine. The pKA value of A61603 was 6.93 +/- 0.19 microM (n=6). Antagonists, BMY 7378, WB 4101 and 5-methylurapidil, caused a parallel shift to the right of the concentration-response curve to A61603 with pA2 values of 6.62, 9.27 and 8.86, respectively. Prazosin, BMY 7378 and WB 4101 inhibited phenylephrine induced contraction with pA2 values of 9.47, 7.17 and 9.73, respectively. The pA2 values obtained for 5-methylurapidil, WB 4101, BMY 7378 and prazosin against alpha1-adrenoceptor agonists were significantly correlated with pKi values (Zhu, Zhang & Han, 1997, Eur. J. Pharmacol.329, 55-61) for the cloned alpha1a-adrenoceptor but not with the cloned alpha1b- or alpha1d-adrenoceptor. BMY 7378, a selective alpha1D-adrenoceptor antagonist, was significantly more potent against the nonsubtype selective agonist phenylephrine than to A61603. Chloroethylclonidine (50 microM for 10 min) did not affect contractile responses to A61603, but caused a significant inhibition of contractile responses to phenylephrine. In conclusion, it appears that alpha1A- and alpha1D-adrenoceptors play a role in adrenergic mediated contraction in the bovine tail artery.
伊奥迪娜，M. V.，戴尔，D. C. 牛尾动脉中α1-肾上腺素能受体亚型的药理学特性。《兽医药理学与治疗学杂志》25卷，363 - 369页。本研究的目的是确定牛尾动脉中存在的介导对肾上腺素能激动剂收缩反应的α1-肾上腺素能受体亚型。与去甲肾上腺素和去氧肾上腺素相比，α1A选择性激动剂A61603的效力更强。A61603的pKA值为6.93±0.19微摩尔（n = 6）。拮抗剂BMY 7378、WB 4101和5-甲基尿嘧啶导致对A61603的浓度-反应曲线平行右移，pA2值分别为6.62、9.27和8.86。哌唑嗪、BMY 7378和WB 4101抑制去氧肾上腺素诱导的收缩，pA2值分别为9.47、7.17和9.73。5-甲基尿嘧啶、WB 4101、BMY 7378和哌唑嗪针对α1-肾上腺素能受体激动剂获得的pA2值与克隆的α1a-肾上腺素能受体的pKi值（朱、张和韩，1997年，《欧洲药理学杂志》329卷，55 - 61页）显著相关，但与克隆的α1b-或α1d-肾上腺素能受体的pKi值不相关。选择性α1D-肾上腺素能受体拮抗剂BMY 7378对非亚型选择性激动剂去氧肾上腺素的效力比对A61603显著更强。氯乙可乐定（50微摩尔，作用10分钟）不影响对A61603的收缩反应，但导致对去氧肾上腺素收缩反应的显著抑制。总之，看来α1A-和α1D-肾上腺素能受体在牛尾动脉肾上腺素能介导的收缩中起作用。
