PHOTO-RELEASED INTRACELLULAR CA2-PIG ORGAN OF CORTI( EVOKES REVERSIBLE MECHANICAL RESPONSES IN SUPPORTING CELLS OF THE GUINEA)

Loaded under whole cell patch-clamp configuration, the caged Ca2+ mole cule DM-nitrophen was used to increase [Ca2+](i) rapidly and reversibl y in isolated Deiters cells of the organ of Corti. Photolysis of DM-ni trophen increased [Ca2+](i) from resting concentrations of 20-50 nM to values above mu M, as measured with the fluorescent indicator Fluo-3. Immediately after the photoliberation of Ca2+ a movement of the head of the phalangeal process could be observed in 75% of cells (n=28). Th is mechanical movement, with an amplitude ranging between 0.5 to 1 mu m within few hundred of ms, consisted of an extension of the phalanges away from the cell body. Measurement of phalangeal stiffness in trans versal flexion toward the cell body ranged between 15-440 pN/mu m. Sti ffness can increase by 28 to 51% after rising [Ca2+](i). The results s uggest Ca2+ as a potential intracellular messenger for active mechanic al responses in Deiters cells. (C) 1994 Academic Press, Inc.