The electrical properties and responses to nerve stimulation of the proximal urethra of the male rabbit
The electrical properties and responses to nerve stimulation of the proximal urethra of the male rabbit
复制标题
DOI：
10.1046/j.1464-410x.1997.00105.x
复制
发表时间：
1997-04-01
期刊：
影响因子：
--
通讯作者：
Ito, Y
中科院分区：
文献类型：
--
作者：
Creed, KE;Oike, M;Ito, Y
目的探讨作用于近端尿路平滑肌细胞的神经递质的性质及其对神经刺激的机械反应的电活动。材料与方法采用微电极和双蔗糖间隙技术记录雄性兔近端尿路纵条的电活动，用200mU S脉冲刺激壁内神经。结果灌流液中加入选择性影响神经传递的药物。结果心肌细胞静息电位平均值为-39 mV，自发动作电位少见。去甲肾上腺素可增加动作电位频率而不去极化，三磷酸腺苷引起去极化，动作电位频率增加。50%的细胞可记录到小的(小于或等于16 mV)自发去极化和超极化，也可记录到大的(小于或等于40 mV)超极化。电刺激可引起兴奋性和抑制性连接电位(EBP和IJP)。大多数ECCP在500ms内达到最大值，以200-300ms的时间常数衰变，并被α，β-亚甲基ATP阻断。IJP的潜伏期为>；1 S，波幅和时程变化较大。在N-硝基-L-精氨酸甲酯(L)存在下，仍可记录到IJP。在双蔗糖间隙中，去极化和相关收缩被α，β-亚甲基三磷酸腺苷减弱。酚妥拉明的作用进一步减弱，剩余的反应被阿托品阻断。单一刺激可产生大的超极化反应，但随着重复刺激，这种超极化程度逐渐降低。结论上尿路由三磷酸腺苷、乙酰胆碱和去甲肾上腺素3种神经递质参与的兴奋性神经支配，抑制与超极化有关，超极化至少部分由非硝能神经引起。
Objective To identify the nature of neurotransmitters acting on the smooth muscle cells of the proximal urethra and the electrical activity underlying the mechanical responses to nerve stimulation.Materials and methods The electrical activity of longitudinal strips of proximal urethra obtained from male rabbits was recorded with microelectrode and double sucrose-gap techniques, Intramural nerves were stimulated with 200 mu s pulses. Drugs which selectively affected neurotransmission were added to the perfusing fluid.Results The mean resting potential of smooth muscle cells was -39 mV and they had infrequent spontaneous action potentials. The frequency was increased by noradrenaline without depolarization; ATP produced depolarization with increased action-potential frequency. Small (less than or equal to 16mV) spontaneous depolarizations and hyperpolarizations could be recorded from < 50% of cells; large (less than or equal to 40 mV) hyperpolarizations also occurred. Electrical stimulation envoked excitatory and inhibitory junction potentials (EJPs and IJPs). Most EJPs reached a maximum within 500 ms, decayed with a time-constant of 200-300 ms and were blocked by alpha,beta-methylene ATP. IJPs had a latency of > 1 s and showed much variation in amplitude and duration. IJPs could still be recorded in the presence of N-nitro-L-arginine methyl ester (L-NAME). In the double sucrose-gap, depolarization and associated contraction were reduced by alpha,beta-methylene ATP. Further reduction occurred with phentolamine and the remaining response was blocked by atropine. A large hyperpolarization could occur in response to a single stimulus but this decreased progressively with repeated stimulation. The hyperpolarization was partially blocked by L-NAME.Conclusions The proximal urethra receives excitatory innervation involving three neurotransmitters, i.e. ATP, acetylcholine and noradrenaline, and inhibition is associated with hyperpolarization which results at least in part from action of non-nitrergic nerves.