Ganglion cells of the myentric plexus of the guinea-pig small intestine were studied with intracellular recording methods. 2. Electrical stimulation of the interganglionic connectives elicited slow synaptic excitation (slow e.p.s.p.) that was associated with an increase in the input resistance of the cell. The slow e.p.s.p.s continued for several seconds after termination of stimulation, and they occurred only in neurones in which prolonged hyperpolarizing after-potentials followed an action potential. 3. Superfusion of the neurones with solutions containing either 1-5 mM-Mn2+ or 16 mM-Mg2+ and 1 mM-Ca2+ mimicked the slow e.p.s.p. The common characteristics of Mn2+, Mg2+ and the slow e.p.s.p. were: (a) depolarization of the membrane potential, (b) increased input resistance of the cell, (c) augmented excitability, (d) blockade of post-pike hyperpolarizing potentials and (e) reversal potential between -70 and -75 mV. 4. Analyses based on the 'constant field equation' indicated that the permeability ratios of K+ to other permeant ionic species were reduced when Ca2+ influx was blocked by Mn2+ or Mg2+. 5. The organic Ca antagonist D-600 did not affect the neurones. 6. The results suggest that slow synaptic modulation of excitability within the myenteric plexus involves a reduction of both resting GK and post-spike GK which is secondary to suppression of Ca2+ influx by the neurotransmitter for the slow e.p.s.p.
摘要
采用细胞内记录方法对豚鼠小肠肌间神经丛的神经节细胞进行了研究。2. 对神经节间连接进行电刺激可引发缓慢的突触兴奋（缓慢兴奋性突触后电位），这与细胞输入电阻的增加有关。刺激终止后，缓慢兴奋性突触后电位可持续数秒，且仅发生在动作电位后跟随有长时间超极化后电位的神经元中。3. 用含1 - 5 mM - Mn²⁺或16 mM - Mg²⁺和1 mM - Ca²⁺的溶液对神经元进行灌流，可模拟缓慢兴奋性突触后电位。Mn²⁺、Mg²⁺和缓慢兴奋性突触后电位的共同特征为：(a) 膜电位去极化；(b) 细胞输入电阻增加；(c) 兴奋性增强；(d) 动作电位后超极化电位被阻断；(e) 反转电位在 - 70至 - 75 mV之间。4. 基于“恒定场方程”的分析表明，当Ca²⁺内流被Mn²⁺或Mg²⁺阻断时，K⁺与其他通透离子种类的通透率比值降低。5. 有机钙拮抗剂D - 600对神经元无影响。6. 结果表明，肌间神经丛内兴奋性的缓慢突触调制涉及静息钾电导和动作电位后钾电导的降低，这是由于缓慢兴奋性突触后电位的神经递质抑制Ca²⁺内流所致。
