Removal of extracellular chloride suppresses transmitter release from photoreceptor terminals in the mudpuppy retina

The removal of extracellular Cl- ions blocks the release of the photoreceptor transmitter L-glutamate from the photoreceptors to the horizontal, ON bipolar and OFF bipolar cells in the mudpuppy retina. The block of L-glutamate suppresses the inward currents in the horizontal and OFF bipolar cells. However, the OFF cells still show light-induced voltage responses due to an increase in the input resistance. The absence of extracellular Cl- blocks the outward current in some cells.