title: TEA-sensitive currents contribute to membrane potential of organ surface primo-node cells in rats.
abstract: The primo-vascular (Bonghan) tissue has been identified in most tissues in the body, but its structure and functions are not yet well understood. We characterized electrophysiological properties of the cells of the primo-nodes (PN) on the surface of abdominal organs using a slice patch clamp technique. The most abundant were small round cells (~10 μm) without processes. These PN cells exhibited low resting membrane potential (-36 mV) and did not fire action potentials. On the basis of the current-voltage (I-V) relationships and kinetics of outward currents, the PN cells can be grouped into four types. Among these, type I cells were the majority (69%); they showed strong outward rectification in I-V relations. The outward current was activated rapidly and sustained without decay. Tetraethylammonium (TEA) dose-dependently blocked both outward and inward current (IC(50), 4.3 mM at ± 60 mV). In current clamp conditions, TEA dose-dependently depolarized the membrane potential (18.5 mV at 30 mM) with increase in input resistance. The tail current following a depolarizing voltage step was reversed at -27 mV, and transient outward current like A-type K(+) current was not expressed at holding potential of -80 mV. Taken together, the results demonstrate for the first time that the small round PN cells are heterogenous, and that, in type I cells, TEA-sensitive current with limited selectivity to K(+) contributed to resting membrane potential of these cells.
authors.affiliation: Laboratory of Veterinary Pharmacology, Research Institute of Veterinary Science, College of Veterinary Medicine, Seoul National University, 599 Gwanak-Ro, Gwanak-Gu, Seoul 151-742, Republic of Korea.
authors.forename: Jae-Hong
authors.initials: JH
authors.lastname: Choi
authors.forename: Chae Jeong
authors.initials: CJ
authors.lastname: Lim
authors.forename: Tae Hee
authors.initials: TH
authors.lastname: Han
authors.forename: Seul Ki
authors.initials: SK
authors.lastname: Lee
authors.forename: So Yeong
authors.initials: SY
authors.lastname: Lee
authors.forename: Pan Dong
authors.initials: PD
authors.lastname: Ryu
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004594:Electrophysiology; D005260:Female; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D019789:Tetraethylammonium / Q000494:pharmacology*
chemical_list: D019789:Tetraethylammonium