title: Ionic currents in rat pulmonary and mesenteric arterial myocytes in primary culture and subculture.
abstract: The electrophysiological properties of cultured single vascular smooth muscle (VSM) cells from rat pulmonary (PA) and mesenteric (MA) arteries were studied using the whole cell patch-clamp technique. Cells were studied at 3-7 days as primary cultures, or were replated after 10-20 days and subcultured for 2-5 days. In the standard physiological bath solution (containing 1.8 mM Ca2+), and with 125 mM K+ + 10 mM ethylene glycol-bis(beta-aminoethyl ether)- N,N,N',N'-tetraacetic acid (EGTA)-filled pipettes, both PA and MA primary cultured cells had high input resistances (mean = 2-3 G omega) and resting membrane potentials of about -40 mV. The cells were clamped at a holding potential of -70 mV. Depolarization to -20 mV or more evoked a transient inward current (Iin) that was eliminated in Ca(2+)-free bath solution; this indicates that Iin was carried by Ca2+. Iin was substantially smaller in subcultured cells from both PA and MA. Depolarization also activated three components of outward current (Iout) in primary cultured PA and MA cells: a rapidly inactivating transient component (Irt), a slowly inactivating transient component (Ist), and a steady-state (noninactivating) component (Iss). All three components of Iout were inhibited to varying degrees by 5 mM 4-aminopyridine and were eliminated by replacing intracellular K+ with Cs+, but were only minimally affected by removal of extracellular Ca2+. These results suggest that this Iout was carried by K+ and was voltage gated. Little external Ca(2+)-dependent Iout was observed under these conditions, but a substantial Ca(2+)-dependent component was seen when the EGTA concentration in the pipettes was reduced to 0.1 mM.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Physiology, University of Maryland School of Medicine, Baltimore 21201.
authors.forename: X J
authors.initials: XJ
authors.lastname: Yuan
authors.forename: W F
authors.initials: WF
authors.lastname: Goldman
authors.forename: M L
authors.initials: ML
authors.lastname: Tod
authors.forename: L J
authors.initials: LJ
authors.lastname: Rubin
authors.forename: M P
authors.initials: MP
authors.lastname: Blaustein
mesh_terms: D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000502:physiology*; D002462:Cell Membrane / Q000502:physiology; D002478:Cells, Cultured; D003584:Cytological Techniques; D004553:Electric Conductivity; D066298:In Vitro Techniques; D008638:Mesenteric Arteries / Q000166:cytology / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000502:physiology*; D011188:Potassium / Q000502:physiology*; D011651:Pulmonary Artery / Q000166:cytology / Q000502:physiology*; D051381:Rats
chemical_list: D015761:4-Aminopyridine; D011188:Potassium; D002118:Calcium