ABSTRACT
Objective To investigate the effect of channel density on the gating properties of Anoctamin 1(Ano1,TMEM16A)Ca2+?activated chlo?ride channel. Methods Ano1 expression plasmids were transiently transfected into HEK293 cells. High density and low density of Ano1 was ob?tained after expressing the protein for 24 h and 6 h,respectively. Electrophysiological recordings were performed in the whole?cell patch clamp con?figuration. The activation kinetics of current traces was fitted by exponentials. Results The current density was significantly higher in cells express?ing Ano1 for 24 h than those expressing Ano1 for 6 h(P0.05). Conclusion Our findings suggested that chan?nel density regulates the gating of Ano1. High channel density promotes activation of Ano1.
ABSTRACT
Objective To observe the effect of ACh on outwardly rectifying potassium currents in isolated outer hair cells(OHCs) with variant length and to analyze effects of ACII on kinetics of the currents. Methods The whole cell patch-clamp technique was used. Results 100 ?mol/L ACh induced greater effects on outwardly rectifying potassium currents in short OHCs. The maximal amplitude of the outward currents increased by 34.8% in the presence of 100 ?mol/L ACII when conditioning potential was 50 mV. ACh effects on the peak currents were greater when compared to the effects on the steady-state currents and changed the shapes of the currents. ACII caused a hyperpolarizing shift of zero current potential of 5 mV. Kinetics of the currents were changed by 100 ?mol/L ACh which induced significantly more hyperpolarizing than control, with increased potential sensitivity of activation, V1/2(Ach) =(-52.38 ? 3.98) mV, SACh =(40 ? 4.14) mV(n= 5). Conclusion ACh increased the conductance of outwardly rectifying K + channel in a voltage dependent manner and caused a hyperpolarizing shift of activation potential. Effect of ACh was to hyperpolarize the membrane potential of OHCs from rest.