[Analysis of current fluctuations shunted from small portions of the membrane of a nerve cell soma].

A method was developed to allow the registration of ionic current through the small areas of the membrane (10 mu2). The aim of the method is to obtain information on the properties of single ionic channels by the fluctuation analysis. The current through single Ca channel while transferring Ba (130 mM in the external media) is 0.21 +/- 0.06 X 10(-12) A according to tentative estimation. The corresponding value for Ca transfer is 0.1 X 10(-12) A. The upper limit for the single Ca channel conductance value is gCa less than or equal to 0.6 X 10(-12) PHI-1.