title: Digital processing of the current noise evoked by kainate in cerebellar granule cells.
abstract: Current induced in cultured cerebellar granule cells by the bath application of kainate (500 microM) was measured using the conventional patch-clamp technique. Two different kinds of responses were observed after the agonist perfusion. Some cells exhibited small inward whole-cell currents: 116 +/- 40 pA (7 cells) at a clamp potential of -60 mV; in other cells, the agonist induced significantly larger currents: 420 +/- 35 pA (6 cells) at a clamp potential of -60 mV. The current flowing in the agonist-activated ionic channels was indirectly estimated by processing the fluctuations of whole-cell current by means of an original parametric method. Mean conductance of the underlying channels was then determined from the single-channel current estimated at different clamp potentials. In the cells exhibiting small inward currents, the mean conductance was equal to 0.5 +/- 0.2 pS (7 cells), whereas in the cells with large inward currents it was 3 +/- 0.4 pS (6 cells). This result gives a coherent explanation of the different kinds of responses observed at macroscopic level in the whole-cell current and confirms that kainate-activated channels can exhibit different levels of conductance.
authors.affiliation: Department of Electronics, Computer Science and Systems, University of Bologna, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Cavalcanti
authors.forename: C
authors.initials: C
authors.lastname: Zona
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects*; D015640:Ion Channel Gating / Q000187:drug effects*; D017136:Ion Transport / Q000187:drug effects / Q000502:physiology; D007608:Kainic Acid / Q000378:metabolism / Q000494:pharmacology*; D008954:Models, Biological; D018408:Patch-Clamp Techniques; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar; D012815:Signal Processing, Computer-Assisted
chemical_list: D007608:Kainic Acid