title: Ionophore monensin induces Na+-dependent secretion from rabbit neutrophils. requirement for intracellular Ca2+ stores.
abstract: Rabbit (and human) neutrophils release the secretory enzyme beta-glucuronidase when treated with the ionophore monensin in the presence of Na+. Release of beta-glucuronidase occurs without loss of the cytosol enzyme lactate dehydrogenase and a number of other features of the release process lead us to conclude that a normal exocytotic mechanism is involved. These include sensitivity to metabolic inhibition, enhancement of release induced by cytochalasin B and a requirement for internal sources of Ca2+ when the cells are stimulated with monensin in the absence of extracellular Ca2+. The release process due to monensin differs from that due to receptor directed agonists such as fMet-Leu-Phe and the Ca2+ ionophores A23187 and ionomycin in respect of a prolonged time-course which extends over 20 min; nor do monensin-stimulated neutrophils generate the superoxide anion. The results are discussed in the light of reports which indicate a rôle for Na+ in the activation of neutrophils by other ligands.
mesh_terms: D000818:Animals; D002118:Calcium / Q000097:blood* / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology; D005089:Exocytosis / Q000187:drug effects; D005663:Furans / Q000494:pharmacology*; D005966:Glucuronidase / Q000097:blood* / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000097:blood; D008985:Monensin / Q000494:pharmacology*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology*; D011817:Rabbits; D012964:Sodium / Q000494:pharmacology*; D013045:Species Specificity
chemical_list: D005663:Furans; D003571:Cytochalasin B; D009240:N-Formylmethionine Leucyl-Phenylalanine; D008985:Monensin; D012964:Sodium; D007770:L-Lactate Dehydrogenase; D005966:Glucuronidase; D002118:Calcium