LIGAND-GATED AND VOLTAGE-GATED ION CHANNELS ARE EXPRESSED BY EMBRYONIC MOUSE RETINAL NEURONS

THE present study was intended to investigate whether voltage- and lig and-activated ion channels are expressed during prenatal development b y neurones located in the ganglion cell layer of the mammalian retina. Whole cell patch clamp recordings from presumed mouse retinal ganglio n cells revealed the expression of Na+, K+ and Ca2+ channels, predomin antly of the low-voltage-activated type. Using local application of tr ansmitter substances we further demonstrated that these cells are endo wed with glutamate receptors of the N-methyl-D-aspartate (NMDA) and no n-NMDA type as well as nicotinic acetylcholine, gamma-amino-butyric ac id (GABA)(A) and glycine receptors. Voltage-gated conductances probabl y underlie spontaneous action potential generation by embryonic gangli on cells. The early expression of transmitter-gated ion channels indic ates important functions of these channels in cell differentiation pro cesses.