title: Histamine-activated, non-selective cation currents and Ca2+ transients in endothelial cells from human umbilical vein.
abstract: Permeation properties and modulation of an ionic current gated by histamine were measured in single endothelial cells from human umbilical cord veins by use of the patch-clamp technique in the ruptured-whole-cell mode or using perforated patches. We combined these current measurements with a microfluorimetric method to measure concomitantly free intracellular calcium concentration ([Ca2+]i). Application of histamine induced an intracellular calcium transient and an ionic current that reversed near 0 mV. The amplitude of the current ranged from -0.2 to -2 nA at -100 mV. The tonic rise in [Ca2+]i and the ionic current are partly due to Ca2+ influx. This Ca2+ entry pathway is also permeable for Ba2+ and Mn2+. The amplitude of the histamine-activated current was also closely correlated with the amplitude of the concomitant Ca2+ transient, suggesting that the latter is at least partially due to Ca2+ influx through histamine-activated channels. The reversal potential of the histamine-induced current was 7.6 +/- 4.1 mV (n = 14) when the calcium concentration in the bath solution ([Ca2+]o) was 1.5 mmol/l. With 10 mmol/l [Ca2+]o it was -13.7 +/- 4.7 mV and shifted to + 13.0 +/- 1.5 mV in nominally Ca(2+)-free solution (n = 3 cells). The amplitude of the current in Ca(2+)-free solution was enhanced compared to that in 10 mmol/l [Ca2+]o. The shift of the reversal potential and the concomitant change of the current amplitude suggest that the channel is permeable for calcium but has a smaller permeability for calcium than for monovalent cations.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Max Planck Group Molecular and Cellular Physiology, K. U. Leuven, Belgium.
authors.forename: B
authors.initials: B
authors.lastname: Nilius
authors.forename: G
authors.initials: G
authors.lastname: Schwartz
authors.forename: M
authors.initials: M
authors.lastname: Oike
authors.forename: G
authors.initials: G
authors.lastname: Droogmans
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D002413:Cations, Divalent / Q000494:pharmacology; D004594:Electrophysiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D006632:Histamine / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D007546:Isoquinolines / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009761:Nystatin / Q000494:pharmacology; D010703:Phorbol Esters / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011247:Pregnancy; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D015398:Signal Transduction / Q000187:drug effects; D014471:Umbilical Veins / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: D015220:Calcium Channels; D002413:Cations, Divalent; D007473:Ion Channels; D007546:Isoquinolines; D010703:Phorbol Esters; D010879:Piperazines; D009761:Nystatin; D006632:Histamine; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D011493:Protein Kinase C