CYTOCHALASIN-B FACILITATES THE INHIBITION OF HUMAN POLYMORPHONUCLEAR LEUKOCYTE GENERATION OF SUPEROXIDE BY VERAPAMIL

  • 1 January 1984
    • journal article
    • research article
    • Vol. 103  (6) , 949-958
Abstract
Several functions of the human neutrophil are dependent on extracellular Ca for optimal activation. The Ca dependency of human polymorphonuclear leukocyte (PMN) superoxide generation in response to opsonized zymosan particles and its modulation by the Ca channel antagonist verapamil was studied. PMN were isolated from anticoagulated blood after Ficoll-Hypaque density centrifugation. The isolated PMN were incubated with opsonized zymosan particles. The superoxide anion generated was measured by a cytochrome C reduction assay. When PMN were incubated with opsonized zymosan in a Ca-free buffer, there was 0.45 .+-. 0.06 nmol of cytochrome C reduced/1 .times. 106 PMN per min. This increased to 0.76 .+-. 0.12 mol/1 .times. 106 PMN per min when 0.6 mmol/l Ca2+ was present. If the PMN were incubated with cytochalasin B (5 .mu.g/ml), the generation of superoxide anion was further enhanced. If the same experiments were conducted in the presence of verapamil, 100 .mu.mol/l, superoxide generation was inhibited by 51.5% .+-. 8.4%. For verapamil to inhibit superoxide generation, cytochalasin B was necessary. Verapamil-sensitive Ca channels may exist in human PMN and the demonstration of their presence is cytochalasin B-dependent.