Diverse involvements of Ni protein in superoxide anion production in polymorphonuclear leukocytes depending on the type of membrane stimulants.

Effects of islet-activating protein (IAP) were examined to assess the involvement of the guanine nucleotide-binding regulatory protein responsible for inhibition of adenylate cyclase system (Ni protein) in the superoxide anion (O-2) production in polymorphonuclear leukocytes (PMNL) stimulated with various agents. N-Formyl-methionyl-leucyl-phenylalanine (FMLP)-stimulated O-2 production was inhibited by the pretreatment with IAP. O-2 production induced by each of phorbol myristate acetate, concanavalin A, and A23187, however, was rather resistant to the pretreatment with IAP. This observation indicates that the Ni protein does not involve in the common pathway for the O-2 production. in PMNL, and the involvement is rather specific for the FMLP-induced production. O-2 production in PMNL stimulated with various membrane perturbing agents was also diverse in the requirement of extracellular Ca2+.