Suzuki N, Gomi Y
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kanazawa University, Japan.
Jpn J Pharmacol. 1989 Jan;49(1):59-65. doi: 10.1254/jjp.49.59.
Effects of nifedipine (10(-8)-10(-6) M), verapamil (10(-6)-3 x 10(-5) M) and Bay k 8644 (10(-7) M) on the contractions induced by transmural nerve stimulation or agonists were investigated in the circular smooth muscle of guinea pig vas deferens using a ring preparation. Transmural stimulation (20 Hz for 20 sec) produced biphasic contractions consisting of initial phasic and secondary tonic components. Nifedipine preferentially inhibited the tonic component and norepinephrine (NE)-induced contractions over the phasic component and beta, gamma-methylene ATP (mATP)-induced contractions. Nifedipine suppressed the enhancing effect of NE on the mATP-induced contractions. The tonic component and NE-induced contractions were inhibited by verapamil in a similar dose range. Verapamil slightly inhibited the phasic component, but rather enhanced mATP-induced contractions. Bay k 8644 slightly increased the phasic component and mATP-induced contractions in the presence of prazosin. Bay k 8644 slowed the relaxation of the tonic component, thereby prolonging the tonic component. Bay k 8644 also prolonged the duration of NE-induced contractions. These results, except for the contradictory effects of verapamil between the phasic component and mATP-induced contractions, are consistent with the claim that ATP and NE are responsible for the generation of phasic and tonic component, respectively, in the circular muscle of guinea pig vas deferens.
采用离体血管环标本，研究硝苯地平（10⁻⁸ - 10⁻⁶ M）、维拉帕米（10⁻⁶ - 3×10⁻⁵ M）和Bay k 8644（10⁻⁷ M）对豚鼠输精管环行平滑肌经壁神经刺激或激动剂诱导收缩的影响。经壁刺激（20 Hz，持续20秒）产生双相收缩，包括初始的相性收缩成分和继发性紧张性收缩成分。硝苯地平优先抑制紧张性收缩成分以及去甲肾上腺素（NE）诱导的收缩，而对相性收缩成分和β,γ-亚甲基ATP（mATP）诱导的收缩抑制作用较弱。硝苯地平抑制了NE对mATP诱导收缩的增强作用。维拉帕米在相似剂量范围内抑制紧张性收缩成分和NE诱导的收缩。维拉帕米对相性收缩成分有轻微抑制作用，但反而增强了mATP诱导的收缩。在存在哌唑嗪的情况下，Bay k 8644轻微增加相性收缩成分和mATP诱导的收缩。Bay k 8644减缓紧张性收缩成分的舒张，从而延长紧张性收缩成分的持续时间。Bay k 8644还延长了NE诱导收缩的持续时间。除了维拉帕米对相性收缩成分和mATP诱导收缩的矛盾作用外，这些结果与以下观点一致：在豚鼠输精管环行平滑肌中，ATP和NE分别负责相性收缩成分和紧张性收缩成分的产生。
