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Lookup NU author(s): Dr Gary Green, Dr David Sanders
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Transient outward currents were characterized with twin electrode voltage clamp techniques in isolated F76 and D1 neuronal membranes (soma only) of Helix aspersa subesophageal ganglia. In this study, in addition to the transient outward current (A-current, IA) described by Connor and Stevens (1971b), another fast outward current, referred to as IAdepol here, is described for the first time. This is similar to the current component characterized in Aplysia (Furukawa, Kandel & Pfaffinger, 1992). The separation of these two current components was based on activation and steady-state inactivation curves, holding potentials and sensitivity to 4-aminopyridine (4-AP). In contrast to IA, IAdepol did not require hyperpolarizing conditioning pulses to remove inactivation; it was evoked from a holding potential of -40 mV, at which IA is completely inactivated. IAdepol shows noticeable activation at around -5 mV, whereas IA activates at around -50 mV. The time courses of IAdepol activation and inactivation were similar but slower than IA. It was found that IAdepol was more sensitive than IA to 4-AP. 4-AP at a concentration of 1 mM blocked IAdepol completely, whereas 5-6 mm 4-AP was needed to block IA completely. This current is potentially very important because it may, like other A currents, regulate firing frequency but notably, it does not require a period of hyperpolarization to be active.
Author(s): Sanders DJ; Green GGR; Bal R; Janahmadi M
Publication type: Article
Publication status: Published
Journal: Journal of Membrane Biology
Year: 2001
Volume: 179
Issue: 1
Pages: 71-78
Print publication date: 01/01/2001
ISSN (print): 0022-2631
ISSN (electronic): 1432-1424
Publisher: Springer New York LLC
URL: http://dx.doi.org/10.1007/s002320010038
DOI: 10.1007/s002320010038
PubMed id: 11155211
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