title: Voltage-activated cation transport in human erythrocytes.
abstract: We report here the effects of membrane potential on the permeability of the human erythrocyte to Na, K, and Ca. Membrane potential was changed either by varying the K concentration gradient in the presence of valinomycin or by varying the concentration gradient of the permeant anion nitrate in the presence of 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. When the membrane potential was changed from inside negative (-10 mV) to inside positive (greater than 40 mV), influx, efflux, and net flux of Na and K increased. Marked net cation loss and cell shrinkage occurred in the absence of a chemical gradient for Na and K. This voltage-dependent increase in Na and K conductance is partially inhibited by 10 microM ruthenium red and persists when the membrane potential is returned to -10 mV after transient exposure to inside-positive potentials. A similar voltage-dependent behavior was found for Ca influx. The voltage-activated Ca influx is almost completely inhibited by 10 microM ruthenium red.
authors.affiliation: Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: J A
authors.initials: JA
authors.lastname: Halperin
authors.forename: C
authors.initials: C
authors.lastname: Brugnara
authors.forename: M T
authors.initials: MT
authors.lastname: Tosteson
authors.forename: T
authors.initials: T
authors.lastname: Van Ha
authors.forename: D C
authors.initials: DC
authors.lastname: Tosteson
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D002412:Cations / Q000378:metabolism; D002712:Chlorides / Q000494:pharmacology; D004553:Electric Conductivity; D004594:Electrophysiology; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D008704:Methazolamide / Q000494:pharmacology; D010539:Permeability; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
chemical_list: D002412:Cations; D002712:Chlorides; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D012964:Sodium; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D011188:Potassium; D002118:Calcium; D008704:Methazolamide