Application oscillatory voltage changes to membrane patches of the lateral wall of outer auditory sensory cells produced movements analogous to the electrically evoked motile responses of intact cells is indicating that the putative voltage sensitive motor is a local property of any domain of the lateral wall in these cells. We are currently testing the hypothesis that such electrodynamic phenomena may involve electrostrictive as well as piezoelectric properties of the lateral wall. Using patch clamping we recorded selective potassium channel activity with 13OpS unit conductance that showed increased open probability to either increase in intracellular calcium,increase in membrane potential, or by the application of pressure to the recording pipette. This stretch-activated feature of the potassium channels may be conferred by association with elements of a submembranous cytoskeletal network present on the lateral wall of these cells. We postulate that the lateral wall with cortical lattice. pillar structures, stretch activated channels and a voltage sensitive force generating apparatus forms a functional unit involved in a secondary mechano-electro-mechanical transduction process responsible for fine tuning in the cochlea and complementary to the primary mechanoelectrical transduction process that occurs in the hair bundle. We demonstrated that myosin filaments, which are responsible for a large repertoire of motile activities in muscle and nonmuscle cells, can translocate actin filaments both toward and away from their central bare zone. This bidirectional movement suggests that there is enough flexibility in the head portion of the tightly packed myosin molecule to move actin not only in the expected direction, but also in the direction opposite to that predicted by the structure of muscle--away from the center of the myosin filament.
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