Daniel E E, Davis C, Sharma V
Department of Neuroscience, McMaster University Health Sciences Centre, Hamilton, Ont., Canada.
Can J Physiol Pharmacol. 1987 Jul;65(7):1433-41. doi: 10.1139/y87-225.
The effect of PGE2 on neurotransmission in the canine tracheal strip dissected free of epithelium was studied in the single sucrose gap and organ bath. PGE2 was a potent inhibitor of the initiation of excitatory junction potentials (ejps) by just submaximal nerve stimulation. In a concentration of 10(-9) or 10(-8) M PGE2 nearly or completely abolished them. Contractile responses to field stimulation in the sucrose gap at 27 degrees C or in muscle baths at 37 degrees C were also reduced or abolished by PGE2 in the same dose range; reductions were greater at low frequency. Responses to acetylcholine were also depressed but significantly less than to field stimulation. These are consistent with major presynaptic as well as some postsynaptic inhibitory actions of PGE2. No evidence was obtained that endogenous PGE2 affected excitatory junction potentials and contractions; i.e. they were stable for hours and unaffected by indomethacin 10(-6) and 10(-5) M under our conditions. Post-stimulus potentiation of ejps amplitude, maximum at 10 s, was observed and became more marked after the first ejp had been markedly reduced or abolished by PGE2. This potentiation was unaffected by indomethacin. It was suggested that a presynaptic process inhibited by PGE2 might participate in this potentiation. The canine trachea is a useful preparation when studied under the experimental condition used here for study of effects of products of arachidonate on neurotransmission.
在单蔗糖间隙和器官浴中研究了前列腺素E2（PGE2）对无上皮犬气管条神经传递的影响。PGE2是一种强效抑制剂，能抑制仅略低于最大强度的神经刺激引发的兴奋性接头电位（ejps）。浓度为10^(-9)或10^(-8) M的PGE2几乎或完全消除了这些电位。在27℃的蔗糖间隙或37℃的肌肉浴中，PGE2在相同剂量范围内也能降低或消除对场刺激的收缩反应；低频时降低幅度更大。对乙酰胆碱的反应也受到抑制，但明显小于对场刺激的抑制。这些结果与PGE2的主要突触前以及一些突触后抑制作用一致。未获得内源性PGE2影响兴奋性接头电位和收缩的证据；即在我们的条件下，它们数小时内稳定，不受10^(-6)和10^(-5) M吲哚美辛的影响。观察到ejps幅度的刺激后增强，在10秒时达到最大值，并且在第一个ejp被PGE2显著降低或消除后变得更加明显。这种增强不受吲哚美辛的影响。有人提出，被PGE2抑制的突触前过程可能参与了这种增强。当在此处使用的实验条件下研究花生四烯酸产物对神经传递的影响时，犬气管是一种有用的标本。
