Summary
Two signals of chemiluminescence are observed when platelets are exposed to arachidonic
acid in the presence of luminol. Three groups of agents interfere with these luminescence
responses. Inhibitors of cyclooxygenase, known to augment the turnover of arachidonic
acid by lipoxygenase, inhibit the first and enhance the second signal of luminescence.
Sodium azide, diamide, NEM, and the endoperoxide analogues U 44069 and U 46619 interfere
with the second luminescence signal but not with the first one nor with the generation
of MDA. These agents may represent selective inhibitors of the lipoxygenase pathway.
Phenidone, nordihydroguaiaretic acid, quercetin, silybin, phenylthiazolyl-thiourea,
and aminotriazole inhibit both luminescence signals promoted by arachidonic acid.
Measurement of luminescence may provide a tool to follow the time course of arachidonic-acid
turnover by prostaglandin synthetase and lipoxygenase in whole cells.
Keywords
Platelets, chemiluminescence of - Chemiluminescence in whole platelets - Lipoxygenase,
inhibition of - Prostaglandin synthetase and luminescence