MELATONIN INDUCES MEMBRANE CONDUCTANCE CHANGES IN ISOLATED RETINAL ROD RECEPTOR-CELLS

Experiments were conducted to verify whether the neurohormone melatoni n influences the membrane conductance of photoreceptors isolated from the frog retina. It has been found that 20 mu M melatonin decreases me mbrane conductances both in the linear and non linear ranges by <0.4 n S. These actions are estimated to produce in dark adapted photorecepto rs an increase of the response to a dim light induced change of the da rk current of about 21%, i.e. from 1.3 to 1.62 mV/pA.