Channels activated by stretch in neurons of a helix snail

Abstract

Single-channel recordings from central neurons of the helix snail, Cepaea nemoralis, revealed two types of channels that could be activated by stretch (i.e., by the membrane deformation produced when suction is applied to the patch pipette). One, a K+ channel (58 pS in physiological solution), was evident in excised and cell-attached patches. Its conductance in symmetrical [K+] solutions indicated a channel of high K+ permeability (PK = 3.4 × 10−13 cm/s). Though osmoregulation has been suggested as a function for such channels, comparisons among molluscs indicate osmotic milieu does not govern their expression; Cepaea is terrestrial, and stretch-activated K+ channels similar to those described here occur in aquatic and marine molluscs. The second type of channel, observed only in excised patches, was Cl− permeant; it had a large conductance (130 pS) and was inactive prior to patch excision. Membrane tension may not be the physiological activator of either the K+ or Cl− channel; the channels are designated as stretch-activated channels on the basis of their experimental behaviour during single-channel recording.Key words: K+ channel, Cl− channel, snail neuron, stretch activation.