LePard K J, Messori E, Galligan J J
Department of Pharmacology and Toxicology, Michigan State University, East Lansing 48824, USA.
Gastroenterology. 1997 Nov;113(5):1522-34. doi: 10.1053/gast.1997.v113.pm9352854.
BACKGROUND & AIMS: Adenosine triphosphate (ATP) acting at P2 receptors mediates some fast excitatory postsynaptic potentials (fEPSPs) in myenteric neurons of guinea pig ileum. The present studies investigate the distribution of purinergic fEPSPs along the length of the gut and characterize the P2-receptor subtype mediating fEPSPs.
Conventional intracellular electrophysiological methods were used to record from myenteric neurons in vitro.
At a membrane potential of -97 +/- 1 mV, the amplitude (25 +/- 1 mV; n = 307) of fEPSPs was similar along the gut. Hexamethonium (100 micromol/L) inhibited fEPSPs in the gastric corpus by 98% +/- 1% (n = 31) and in the duodenum, ileum, taenia coli, proximal colon, and distal colon by 42%-55%. In the presence of hexamethonium, suramin (100 micromol/L) or the P2X antagonist pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS, 10 micromol/L) reduced the control fEPSP amplitude in the duodenum, ileum, taenia coli, proximal colon, and distal colon by 71%-84%. The pharmacology of the purinergic fEPSPs was investigated in detail in the ileum. Noncholinergic fEPSPs were concentration-dependently (1-30 micromol/L) inhibited by PPADS (50%-inhibitory concentration, 3 micromol/L). In addition, alpha,beta-methylene 5'-adenosine triphosphate (1 micromol/L) also reduced purinergic fEPSPs.
Fast EPSPs mediated in part through P2X receptors are prominent in myenteric neurons along the small and large intestines but are rare in the gastric corpus.
三磷酸腺苷（ATP）作用于P2受体，介导豚鼠回肠肌间神经元的一些快速兴奋性突触后电位（fEPSP）。本研究旨在探究嘌呤能fEPSP沿肠道长度的分布情况，并对介导fEPSP的P2受体亚型进行特征描述。
采用传统的细胞内电生理方法在体外记录肌间神经元的电活动。
在膜电位为-97±1mV时，fEPSP的幅度（25±1mV；n = 307）沿肠道相似。六甲铵（100μmol/L）使胃体部的fEPSP抑制98%±1%（n = 31），使十二指肠、回肠、结肠带、近端结肠和远端结肠的fEPSP抑制42% - 55%。在存在六甲铵的情况下，苏拉明（100μmol/L）或P2X拮抗剂磷酸吡哆醛 - 6 - 偶氮苯 - 2',4'-二磺酸（PPADS，10μmol/L）使十二指肠、回肠、结肠带、近端结肠和远端结肠的对照fEPSP幅度降低71% - 84%。在回肠中详细研究了嘌呤能fEPSP的药理学特性。非胆碱能fEPSP被PPADS浓度依赖性（1 - 30μmol/L）抑制（50%抑制浓度为3μmol/L）。此外，α,β-亚甲基5'-三磷酸腺苷（1μmol/L）也可降低嘌呤能fEPSP。
部分通过P2X受体介导的快速兴奋性突触后电位在小肠和大肠的肌间神经元中很突出，但在胃体部很少见。
