Changes in the receptor potential under polarizing currents in two insect receptors

Abstract

A study of the variations of amplitude and shape of receptor potentials (R.P.) under the influence of polarizing currents was made on two insect receptors: an olfactory receptor of tonic type and a mechanoreceptor of phasicotonic type. The polarizations and recordings were made through the same microelectrode, using a Wheatstone bridge. The amplitude of the R.P. increased when the receptors were polarized by a current passing through the receptor in the direction: dendrite to axon except for the second phase of the phasic tonic receptor. Their amplitude was reduced and even inverted by a current flowing in the opposite direction. The global impedance of the receptor and its diminution during a receptor potential obtained by a natural stimulation were estimated. The results obtained for sinusoidal currents of different frequencies are discussed. An interpretation of the results is attempted by comparing them with those for other receptors.