ACTION-POTENTIALS IN AXONLESS HORIZONTAL CELLS ISOLATED FROM THE RABBIT RETINA

Axonless horizontal cells were enzymatically dissociated from the reti nae of adult rabbits. Whole-cell patch-clamp recordings were made on d issociated cells and voltage- and ligand-induced currents were studied . When membrane potential was measured in the current-clamp configurat ion, current pulses injected into the cell induced repetitive action p otentials. When the cells were depolarised by bath application of kain ic acid (KA, 30 mu M), a train of fast-repetitive action potential was evoked. Also, a slow long-lasting calcium action potential kept the c ells depolarised long after the cessation of the KA application. These findings indicate for the first time that horizontal cells of the mam malian retina are able to produce trains of action potentials.