Whole cell membrane currents in cultured pig endocardial endothelial cells.
The whole cell mode of the patch-clamp technique was applied to cultured endocardial endothelial cells from the porcine right ventricle to study their electrophysiological properties. With isotonic pipette and bathing solutions (300-310 mosmol/kgH2O), single endocardial endothelial cells had resting membrane potentials ranging from -20 to -90 mV (mean = -55 +/- 20 mV, n = 48). In voltage-clamp experiments, the main membrane current was an inwardly rectifying K+ current with all characteristics described for the inwardly rectifying K+ current in vascular endothelium. Outward currents at positive clamp potentials were small, but when cell swelling was induced by means of a hypertonic pipette or hypotonic bathing solution and ATP (5 mM) was present in the pipette solution, a large outwardly rectifying current developed. This volume-activated current was insensitive to extracellular K+ or Na+ concentration variations but sensitive to changes in extracellular Cl- concentrations. It was inhibited in the presence of 4,4'-diisothiocyanostilbene-2,2 disulfonic acid (100-300 microM) and flufenamic acid (50-100 microM). Volume-activated Cl- channels are different from the stretch-activated cationic channels described in vascular endothelium and might be involved in the regulation of cell volume or the response to mechanical stretch.
Fransen
P F
PF
Laboratory of Physiology, University of Antwerp, Belgium.
Demolder
M J
MJ
Brutsaert
D L
DL
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D002478:Cells, Cultured; D004553:Electric Conductivity; D004699:Endocardium / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D004727:Endothelium / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D006982:Hypertonic Solutions / Q000494:pharmacology; D011188:Potassium / Q000502:physiology; D012146:Rest; D013552:Swine
D006982:Hypertonic Solutions; D000255:Adenosine Triphosphate; D011188:Potassium