甲氧明诱导兔肛门尾骨肌的节律性活动。

Methoxamine-induced rhythmic activity in rabbit anococcygeus muscle.

Dehpour A R, Tajkhorshid E, Radjaee-Behbahani N, Kheirollahi K

Department of Pharmacology, Faculty of Medicine, Tehran University of Medical Sciences, Iran.

Gen Pharmacol. 1993 Jul;24(4):841-5. doi: 10.1016/0306-3623(93)90157-s.

Abstract

Methoxamine 0.5 microns induced an extremely regular rhythmic activity in isolated rabbit anococcygeus muscle. 2. Prazosin had an inhibitory effect on methoxamine-induced rhythmic contractions. IC50 of prazosin was 7.94 nM. 3. The methoxamine-induced contractions are dependent on extracellular calcium and can be inhibited by the omission of calcium from media or the introduction of verapamil (IC50 = 0.11 microM) or nifedipine (IC50 = 0.21 microM). 4. Application of reserpine made the preparations 40-fold more sensitive to methoxamine. 5. It can be concluded that rhythmic contractions produced by methoxamine are mediated through stimulatory action of methoxamine on alpha-I adrenoceptors and depend on extracellular calcium. 6. Lithium made the muscle more sensitive to methoxamine action. In preincubated muscles with 1, 3 and 5 mM lithium the initiation of contractions occurred at 1.5 x 10(-7), M, 5 x 10(-8) M and 1.5 x 10(-8) M of methoxamine, respectively.

摘要

0.5微克甲氧明可使离体兔肛尾肌产生极其规则的节律性活动。2. 哌唑嗪对甲氧明诱导的节律性收缩有抑制作用。哌唑嗪的半数抑制浓度（IC50）为7.94纳摩尔。3. 甲氧明诱导的收缩依赖于细胞外钙，培养基中去除钙或加入维拉帕米（IC50 = 0.11微摩尔）或硝苯地平（IC50 = 0.21微摩尔）可抑制该收缩。4. 利血平使制剂对甲氧明的敏感性提高40倍。5. 可以得出结论，甲氧明产生的节律性收缩是通过甲氧明对α-1肾上腺素能受体的刺激作用介导的，且依赖于细胞外钙。6. 锂使肌肉对甲氧明的作用更敏感。在分别用1毫摩尔、3毫摩尔和5毫摩尔锂预孵育的肌肉中，收缩起始时甲氧明的浓度分别为1.5×10⁻⁷摩尔、5×10⁻⁸摩尔和1.5×10⁻⁸摩尔。