Ca selectivity of the transduction channels in the hair cells of the frog sacculus

摘要: The extracellular receptor currents evoked by step displacements of the otolithic membrane isolated saccular macula Rana esculenta were recorded under transepithelial voltage clamp conditions. With aim to depolarize hair cells and increase fractional resistance apical membranes, basal side preparation was bathed in saline with an increased K+ concentration (62 mM). This caused a shift non-linear current-voltage relation along axis -51 mV +/- 10 mV; (mean SD; n = 32) reduction 10%. Under these conditions electrical properties are assumed be controlled membranes. effects different concentrations Ca2+ solution on examined. Change (range 3 mM 70 microM) varied at which current zero (Vrev). Fitting modified constant field equation between change Vrev gave estimate PCa/PK transduction channels 212. Furthermore, high relative permeability for other divalent cations (Ba2+, Sr2+) measured, whereas Mn2+ inhibited current. amiloride (IC50 3.2 microM 1.7 nifedipine 1.9 0.6 microM). Reduction 90 standard reduced size 67% 30% (n 17) compared control but did not affect shape relation. Subsequent substitution Na+ further 32% 29% 9), changed into linear diminished adaptation These results indicate that mechano-electrical frog highly selective conductance may influenced monovalent cation species.