Abstract
Dual radiolabel incorporation of [3H]arachidonic acid and [14]palmitate or [14C]stearate by human neutrophils was employed to study both the release and metabolism of arachidonic acid. Results indicate the involvement of a phospholipase A2 mechanism causing [3H]arachidonate release from membrane phospholipid. Phosphatidylinositol and phosphatidylcholine were the sources of [3H]arachidonate; about twice as much radiolabeled phosphatidylinositol was degraded as phosphatidylcholine. Challenge of neutrophils with opsonized zymosan and calcium ionophores caused the release of [3H]arachidonate; however, ionophores but not opsonized zymosan led to the production of [3H]hydroxyicosatetraenoic acid and [3H]dihydroxyicosatetraenoic acid. These products were preferentially released by neutrophils into the extracellular milieu in contrast with free [3H]arachidonate which remained cell associated. One-third of the [3H]hydroxyicosatetraenoic acid but not [3H]dihydroxyicosatetraenoic acid was reincorporated into cellular lipid, primarily phospholipid. No significant production of [3H]prostaglandin or [3H]thromboxane was detected. In contrast to zymosan and ionophore, phorbol myristate acetate, another potent stimulant of neutrophil oxidative metabolism and degranulation, did not release [3H]arachidonate.
Original language | English |
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Pages (from-to) | 7228-7234 |
Number of pages | 7 |
Journal | Journal of Biological Chemistry |
Volume | 256 |
Issue number | 14 |
State | Published - 1981 |
Externally published | Yes |