Ohashi H, Naito K, Takewaki T, Okada T
Jpn J Pharmacol. 1977 Jun;27(3):379-87. doi: 10.1254/jjp.27.379.
Muscle strips from the longitudinal or circular muscle of the chicken rectum were used to determine changes in membrane potential during field stimulation as recorded using the sucrose-gap method. Stimulation with single square pulses (0.1 msec duration) evoked junction potentials elicited by transmitter released from nerve endings. Facilitation in amplitude of excitatory junction potentials (EJPs) was seen during repetitive stimulation in the longitudinal muscle, but in the circular muscle, EJPs reduced. Neither atropine nor hyoscine (up to 10(-5) g/ml) reduced EJPs. These drugs abolished the depression of EJPs in the circular muscle produced by repetitive stimulation. Anticholinesterases (2 X 10(--8)-2 X 10(-6) g/ml) reduced the EJPs. The inhibitory effect was produced without affecting the membrane resistance of smooth muscle and was completely antagonized by atropine (1-(-6) g/ml). Drugs that abolish the adrenergic functions did not affect the EJPs. These results suggest that nerves involved in the EJPs are non-cholinergic and non-adrenergic in nature, and the motor transmission to the smooth muscle may be inhibited by cholinergic nerves, presumably presynaptically.
取自鸡直肠纵肌或环肌的肌条，用于通过蔗糖间隙法记录来测定场刺激期间膜电位的变化。用单个方波脉冲（持续时间0.1毫秒）刺激可诱发由神经末梢释放的递质所引发的接头电位。在纵肌的重复刺激过程中，兴奋性接头电位（EJPs）的幅度出现易化现象，但在环肌中，EJPs降低。阿托品和东莨菪碱（浓度高达10^(-5) g/ml）均未降低EJPs。这些药物消除了重复刺激所导致的环肌中EJPs的抑制作用。抗胆碱酯酶（2×10^(-8) - 2×10^(-6) g/ml）降低了EJPs。这种抑制作用的产生并未影响平滑肌的膜电阻，且被阿托品（10^(-6) g/ml）完全拮抗。消除肾上腺素能功能的药物对EJPs无影响。这些结果表明，参与EJPs的神经在性质上是非胆碱能和非肾上腺素能的，并且向平滑肌的运动传递可能受到胆碱能神经的抑制，推测是突触前抑制。
