Effect of ultrasound on the functional state of nicotinic acetylcholine receptors in molluscan neurons.

The effect of ultrasound (2.64 MHz, 0.5 W/cm2) on acetylcholine-induced (ACh-induced) current and surface distribution of ACh receptors (AChRs) were studied in neurons of the mollusc Helix pomatia. Upon switching on the ultrasound a negligibly small transient two-phase transmembrane current appeared; prolonged (5-25 min) action of beamed ultrasound waves significantly depressed the ACh-induced chloride current and caused the disappearance of functional nicotinic AChRs on parts of the neuronal soma distant from the axon. Pharmacological studies showed that the disappeared AChRs were responsible for changes in membrane permeability for chloride ions (AChRsCl). The results obtained in the present study indicate that ultrasound may be used as a selective inhibitor of AChRsCl in molluscan neurons.