Glycine receptors and transporters on bullfrog retinal Muller cells

Glycine is a principal inhibitory neurotransmitter in the vertebrate retina. We have characterized glycine-induced currents from Muller cells in the bullfrog retinal slice preparation using whole-cell recordings. The glycine-induced current was partially suppressed by strychnine, and the remaining strychnine-resistant component was sacrosine-sensititve, suggesting that these two components may be mediated by glycine receptors and glycine transporters, respectively. Furthermore, the two components were maximal at the inner nuclear layer (INL) and declined asymmetrically as the application site was moved away from the INL to either the external or internal limiting membranes. It is suggested that Muller cells may be involved in glycinergic transmission by communicating with retinal neurons through these receptors and transporters.