Melatonin induces membrane conductance changes in isolated retinal rod receptor cells

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