Miura A, Ukai Y, Matsuzaki T, Ishima T, Hayashi S, Kano S, Kimura K
Research Laboratories, Nippon Shinyaku Co., Ltd., Kyoto, Japan.
Nihon Yakurigaku Zasshi. 1990 Apr;95(4):201-8. doi: 10.1254/fpj.95.4_201.
alpha-Adrenoceptor blocking effects of the cardioselective beta-blocker celiprolol were tested. 1. Celiprolol antagonized the contractions induced by UK-14304, but not those by phenylephrine, in isolated rat tail arteries with a pA2 value of 4.95. 2. In the isolated rat vas deferens, twitch contractions elicited by the transmural electrical stimulation (TS) were almost blocked by TTX (10(-7) M). Clonidine inhibited the TTX-sensitive contraction in a concentration-dependent manner. Celiprolol produced little effect on the inhibitory effects of clonidine. The concentration-inhibition curve of clonidine was shifted to the right by yohimbine (10(-8) M), but not by prazosin (10(-8) M). 3. Although celiprolol slightly increased the 3H-efflux to TS from the [3H]-norepinephrine-loaded rat vas deferens, the increment was not significant. Yohimbine (10(-7) M) significantly increased the 3H-efflux. TTX (10(-7) M) and bretylium (3 x 10(-5) M) blocked the 3H-efflux. 4. In the spinal rat treated with propranolol (3 mg/kg, i.v.) and prazosin (0.1 mg/kg, i.v.), celiprolol (30 and 100 mg/kg, i.v.) and yohimbine (0.1-1 mg/kg, i.v.) inhibited the pressor response to clonidine. 5. These results indicate that celiprolol may have a weak alpha 2-blocking effect which was more effective on postsynaptic alpha 2-receptors than presynaptic ones.
对心脏选择性β受体阻滞剂塞利洛尔的α肾上腺素受体阻断作用进行了测试。1. 在离体大鼠尾动脉中，塞利洛尔能拮抗UK - 14304诱导的收缩，但不能拮抗去氧肾上腺素诱导的收缩，其pA2值为4.95。2. 在离体大鼠输精管中，经壁电刺激（TS）引发的抽搐性收缩几乎被TTX（10⁻⁷ M）阻断。可乐定以浓度依赖方式抑制TTX敏感的收缩。塞利洛尔对可乐定的抑制作用影响很小。可乐定的浓度 - 抑制曲线被育亨宾（10⁻⁸ M）右移，但未被哌唑嗪（10⁻⁸ M）右移。3. 虽然塞利洛尔使[³H] - 去甲肾上腺素负载的大鼠输精管对TS的³H外流略有增加，但增加不显著。育亨宾（10⁻⁷ M）显著增加³H外流。TTX（10⁻⁷ M）和溴苄铵（3×10⁻⁵ M）阻断³H外流。4. 在静脉注射普萘洛尔（3 mg/kg）和哌唑嗪（0.1 mg/kg）处理的脊髓大鼠中，静脉注射塞利洛尔（30和100 mg/kg）和育亨宾（0.1 - 1 mg/kg）可抑制对可乐定的升压反应。5. 这些结果表明，塞利洛尔可能具有较弱的α₂阻断作用，对突触后α₂受体的作用比对突触前α₂受体的作用更有效。
