Calcium-mobilizing agonists stimulate anion fluxes in cultured endothelial cells from human umbilical vein

Academic Article

Abstract

  • The goal of the present studies was to determine whether anion fluxes are involved in thrombin-and histamine-activated signal transduction pathways in human umbilical vein endothelial cells (HUVECs). Iodine ( I) efflux techniques were used to test the sensitivity of anion fluxes to increases in [Ca ] and activation of protein kinase C. HUVECs exhibited constant I efflux rates under basal conditions. Administration of thrombin or histamine stimulated an increase in I efflux rates which returned to control values after approximately 1-2 min. Since both agonists stimulate increases in [Ca ] , we tested the hypothesis that I efflux was sensitive to changes in [Ca ] . When HUVECs were exposed to ionomycin or thapsigargin, the I efflux rate increased and remained elevated for several minutes. In subsequent experiments, HUVECs were incubated with the cell permanent Ca chelator, 1,2-bis-(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid-AM, to buffer changes in [Ca ] . This treatment reduced both basal and thrombin-stimulated I efflux. However, when Ca was removed from the efflux buffer and replaced with EGTA, peak thrombin-stimulated I efflux remained unchanged. This anion efflux was also sensitive to activation of protein kinase C since phorbol 12-myristate 13-acetate and phorbol, 12,13-dibutyrate blunted thrombin-mediated increases in I efflux. Preincubation of HUVECs with protein kinase C inhibitor peptide [19-36] antagonized the phorbol ester-mediated decrease in thrombin-stimulated I efflux. We suggest that I efflux in HUVECs represents a Ca -sensitive anion conductance and that intracellular Ca release, but not extracellular Ca influx, is sufficient to initiate channel activity. © 1994 Springer-Verlag New York Inc. 125 125 2+ 125 125 2+ 125 2+ 125 2+ 2+ 125 2+ 125 125 125 125 2+ 2+ 2+ i i i i
  • Authors

    Digital Object Identifier (doi)

    Pubmed Id

  • 18003392
  • Author List

  • White CR; Brock TA
  • Start Page

  • 171
  • End Page

  • 179
  • Volume

  • 142
  • Issue

  • 2