Collagen-stimulated superoxide production: evidence for coupled mobilization of calcium.
Superoxide production by human neutrophils was stimulated by rat liver collagen. The stimulation was exponentially related to the collagen concentration, with maximal effect at 150 micrograms/ml. The collagen-induced effect was significantly enhanced by the presence of Ca2+ in the medium. Verapamil--a calcium channel blocker--caused a dose-dependent inhibition of superoxide production by collagen-stimulated neutrophils. Collagen-induced stimulation was associated with a transient rise in cytosolic free Ca2+ independent of the presence of Ca2+ in the medium. Depletion of intracellular calcium caused a significant decrease in superoxide activity; however, replenishment of Ca2+ in the medium significantly overcame the inhibition. These changes were associated with a direct binding of [14C]collagen with the neutrophils. Our data suggest that collagen-neutrophil interaction couples superoxide production with the process of Ca2+ mobilization and that this interaction may play a physiologic role in neutrophil stimulation.
Andrabi
K I
KI
Department of Experimental Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Kaul
N
N
Mudassar
S
S
Dilawari
J B
JB
Ganguly
N K
NK
D000818:Animals; D002118:Calcium / Q000097:blood*; D002413:Cations, Divalent; D003094:Collagen / Q000097:blood / Q000302:isolation & purification / Q000494:pharmacology*; D003600:Cytosol / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008099:Liver / Q000737:chemistry; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D011489:Protein Denaturation; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism; D038981:Receptors, Collagen; D013481:Superoxides / Q000097:blood*; D014700:Verapamil / Q000494:pharmacology
D002413:Cations, Divalent; D011956:Receptors, Cell Surface; D038981:Receptors, Collagen; D013481:Superoxides; D004533:Egtazic Acid; D003094:Collagen; D014700:Verapamil; D002118:Calcium