title: Modulation by external Ca2+ and nicardipine of Ca2+ influx and cytosolic concentration in human erythrocytes.
abstract: Variations of Ca2+ influx (evaluated by the initial rate of 45Ca2+ uptake) and cytosolic free Ca2+ concentration ([Ca2+]i, measured with fura-2) were investigated in human erythrocytes. When external Ca2+ concentration ([Ca2+]o) rose from 1 to 2 mM, the initial rate of Ca2+ influx nearly doubled whereas [Ca2+]i increased only by 15%. Nicardipine dose-dependently decreased both initial rate of Ca2+ influx and [Ca2+]i (up to 53 and 18%. respectively at 10(-6) M). The less marked changes in [Ca2+]i than in Ca2+ influx indicate a partial adjustment of the Ca2+ extruding-pump activity to of Ca2+ influx. In vivo administration of nicardipine reduced [Ca2+]i only when its initial value exceeded 80 nM and prevented the rise in [Ca2+]i induced by the increase in [Ca2+]o. Our results indicate that nicardipine may reduce Ca2+ influx in human erythrocytes and participate in the control of [Ca2+]i when elevated.
authors.affiliation: Department of Pharmacology, CNRS 161670. Necker Medical School, Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: David-Dufilho
authors.forename: C
authors.initials: C
authors.lastname: Astarie
authors.forename: M G
authors.initials: MG
authors.lastname: Pernollet
authors.forename: L
authors.initials: L
authors.lastname: Bergougnan
authors.forename: A
authors.initials: A
authors.lastname: Comte
authors.forename: C
authors.initials: C
authors.lastname: Dubray
authors.forename: M A
authors.initials: MA
authors.lastname: Devynck
mesh_terms: D002118:Calcium / Q000097:blood*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D009529:Nicardipine / Q000008:administration & dosage / Q000494:pharmacology*; D014638:Vanadates / Q000494:pharmacology
chemical_list: D015220:Calcium Channels; D014638:Vanadates; D009529:Nicardipine; D002118:Calcium