Patch-clamp study of neurons and glial cells in isolated myenteric ganglia

Most of the physiological information on the enteric nervous system has bee n obtained from studies on preparations of the myenteric ganglia attached t o the longitudinal muscle layer. This preparation has a number of disadvant ages, e.g., the inability to make patch-clamp recordings and the occurrence of muscle movements. To overcome these limitations we used isolated myente ric ganglia from the guinea pig small intestine. In this preparation moveme nt was eliminated because muscle was completely absent, gigaseals were obta ined, and whole cell recordings were made from neurons and glial cells. The morphological identity of cells was verified by injecting a fluorescent dy e by micropipette. Neurons displayed voltage-gated inactivating inward Naand Ca2+ currents as well as delayed-rectifier K+ currents. Immunohistochem ical staining confirmed that most neurons have Na+ channels. Neurons respon ded to GABA, indicating that membrane receptors were retained, Glial cells displayed hyperpolarization-induced K+ inward currents and depolarization-i nduced K+ outward currents. Glia shouted large "passive" currents that were suppressed by octanol, consistent with coupling by gap junctions among the se cells. These results demonstrate the advantages of isolated ganglia for studying myenteric neurons and glial cells.