title: Effect of histamine on the membrane potential of cultured human nonpigmented ciliary epithelial cells.
abstract: The effect of histamine on the membrane potential of cultured human nonpigmented ciliary epithelial cells was examined using intracellular microelectrodes. The resting voltage was Vm = 42 +/- 0.7 mV (n = 41). Histamine (10(-6) mol/l) induced transient hyperpolarization (V = 19.4 +/- 1.2 mV, n = 35) and subsequent depolarization when applied for more than 1 min. The histamine effect was completely inhibited by the H1 antagonist diphenhydramine (10(-6) mol/l), but not influenced by the H2 antagonist cimetidine (up to 10(-3) mol/l). When histamine was applied repeatedly in the absence of external calcium, the amplitude of the hyperpolarization decreased until finally no response was observed. Ba2+ (2 mmol/l) and quinidine (1 mmol/l), both inhibitors of potassium conductance, significantly reduced histamine-induced hyperpolarization. It was also reduced when cells were depolarized by 40 mmol/l extracellular potassium and almost completely abolished in the presence of 80 mmol/l external potassium. We conclude that H1 receptors mediate hyperpolarization by increasing potassium conductance, probably via transient release of intracellularly stored calcium.
authors: Institut für Klinische Physiologie, Universitätsklinikum Steglitz, Freie Universität Berlin, Federal Republic of Germany.
authors: F
authors: F
authors: Stahl
authors: H J
authors: HJ
authors: Garus
authors: A
authors: A
authors: Lepple-Wienhues
authors: M
authors: M
authors: Wiederholt
mesh_terms: D002118:Calcium / Q000502:physiology; D002478:Cells, Cultured; D002924:Ciliary Body / Q000187:drug effects* / Q000502:physiology; D002927:Cimetidine / Q000494:pharmacology; D004155:Diphenhydramine / Q000494:pharmacology; D006632:Histamine / Q000494:pharmacology*; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects*; D008839:Microelectrodes; D010857:Pigment Epithelium of Eye; D011188:Potassium / Q000502:physiology; D011969:Receptors, Histamine H1 / Q000502:physiology
chemical_list: D011969:Receptors, Histamine H1; D002927:Cimetidine; D006632:Histamine; D004155:Diphenhydramine; D011188:Potassium; D002118:Calcium