title: Arachidonic acid-induced LH release is ATP-independent and insensitive to N-ethyl maleimide.
abstract: The mechanism of arachidonic acid (AA)-induced LH release was characterized using sheep pituitary cells in primary culture permeabilized with Staphylococcal alpha-toxin. In intact cells, exogenous AA evoked release of LH in a manner which was partially dependent on extracellular Ca2+. At similar concentrations, AA also caused cell permeabilization as monitored by efflux of [3H]2-deoxyglucose metabolites. In alpha-toxin-permeabilized cells where cytosolic Ca2+ was clamped at resting levels, AA retained its ability to cause LH release. Unlike the stimulation of exocytosis produced by Ca2+, phorbol ester or cyclic AMP, AA-evoked release was independent of ATP and was not inhibited by pretreatment with N-ethyl maleimide. These findings indicated that exogenous AA does not cause LH release by Ca2+ influx or mobilization or by activating protein kinase C. The results suggest that LH release induced by exogenous AA is probably due to its detergent-like properties, and does not represent true exocytosis.
authors.affiliation: Department of Chemical Pathology, University of Cape Town Medical School, Observatory, South Africa.
authors.forename: P V
authors.initials: PV
authors.lastname: Kaye
authors.forename: P A
authors.initials: PA
authors.lastname: van der Merwe
authors.forename: R P
authors.initials: RP
authors.lastname: Millar
authors.forename: J S
authors.initials: JS
authors.lastname: Davidson
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D005033:Ethylmaleimide / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000096:biosynthesis*; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism*; D012756:Sheep / Q000378:metabolism*
chemical_list: D016718:Arachidonic Acid; D000255:Adenosine Triphosphate; D007986:Luteinizing Hormone; D005033:Ethylmaleimide; D002118:Calcium