GADOLINIUM UNCOUPLES MECHANICAL DETECTION AND OSMORECEPTOR POTENTIAL IN SUPRAOPTIC NEURONS

Stretch-sensitive ion channels are ubiquitous, yet evidence of their r ole in mechanotransduction remains scarce. The presence of stretch-ina ctivated cation channels in supraoptic neurons is consistent with the osmoreceptor potentials regulating vasopressin release. However, wheth er osmosensitivity depends on mechanical gating and ion flux through s tretch-inactivated channels is unknown. Here we report that changes in channel open probability associated either with modification of pipet te pressure or with external osmolality selectively result from variat ions in closed time. While channel mechanosensitivity and osmotically evoked changes in cell volume are not affected by gadolinium, similar concentrations of the lanthanide inhibit cation permeation through the single channels and macroscopic osmoreceptor potentials. Mechanotrans duction through stretch-inactivated channels is therefore necessary fo r osmoreception in supraoptic neurons.