title: Ca(2+)-insensitive modulation of a K+ conductance by inositol polyphosphates.
abstract: Macrophages derived from phorbol ester-induced human leukemic (HL-60) cells exhibit a voltage-activated inward rectifying potassium conductance which was modulated by macrophage colony-stimulating factor (Wieland, S. J., Chou, R. H., and Gong, Q. H. (1990) J. Cell. Physiol. 142, 643-651). Roles of intracellular messengers in this regulatory mechanism were investigated. Intracellular dialysis with inositol 1,3,4,5-tetrakisphosphate (IP4) or inositol 1,4,5-trisphosphate during tight-seal whole cell recording produced a rapid increase in the inward rectifying conductance. Changes in intracellular Ca2+ levels alone did not reproduce the stimulatory effect of these modulators. Intracellular dialysis with guanosine 5'-O-(thiotriphosphate) (GTP gamma S) resulted in profound inhibition of this conductance. These data suggest a novel cellular function for inositol polyphosphates, particularly IP4, and show antagonistic modulation with GTP gamma S on a human macrophage inward rectifier.
authors.affiliation: Department of Anatomy, Hahnemann University, Philadelphia, Pennsylvania 19102.
authors.forename: J T
authors.initials: JT
authors.lastname: Wu
authors.forename: Q H
authors.initials: QH
authors.lastname: Gong
authors.forename: R H
authors.initials: RH
authors.lastname: Chou
authors.forename: S J
authors.initials: SJ
authors.lastname: Wieland
mesh_terms: D002118:Calcium / Q000378:metabolism*; D004553:Electric Conductivity; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D007295:Inositol Phosphates / Q000378:metabolism*; D007938:Leukemia / Q000473:pathology; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D008564:Membrane Potentials; D011188:Potassium / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D007295:Inositol Phosphates; C081655:inositol-1,3,4,5-tetrakisphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D016173:Macrophage Colony-Stimulating Factor; D015544:Inositol 1,4,5-Trisphosphate; D011188:Potassium; D002118:Calcium