title: Adrenergic modulation of apoptosis in splenocytes of Xenopus laevis in vitro.
abstract: Impaired and healthy cells undergo suicide using an intrinsic genetic program. Exposure to stress-related alpha2- or beta-adrenergics for 4 or 20 h in vitro had no effect on apoptosis in splenocytes of adult Xenopus laevis, while a 4-hour coincubation of clonidine, an alpha2-agonist, with a calcium ionophore (A23187) or a phorbol diester (PMA), enhanced apoptosis induced by each apoptogen alone. Clonidine did not affect apoptosis stimulated with dexamethasone (DEX), however. Comparable in vitro exposures to isoproterenol, a beta-agonist, reduced apoptotic levels stimulated by all three apoptogens alone. Following 20 h coexposure, clonidine no longer affected A23187-induced apoptosis, but reduced PMA-induced apoptosis, while isoproterenol enhanced apoptosis stimulated with both. Neither agonist modulated apoptosis induced by 20 h of exposure to DEX. Thus, adrenergic agonists modulated apoptosis in cells coexposed to A23187 and PMA, in a time-dependent and adrenoceptor class-dependent fashion. These stress-induced products can affect concurrent apoptosis reversibly over time in vitro, and thus possibly in vivo.
authors.affiliation: Department of Biology, Reed College, Portland, Oreg. 97202-8199, USA.
authors.forename: M
authors.initials: M
authors.lastname: Haberfeld
authors.forename: R O
authors.initials: RO
authors.lastname: Johnson
authors.forename: L N
authors.initials: LN
authors.lastname: Ruben
authors.forename: R H
authors.initials: RH
authors.lastname: Clothier
authors.forename: S
authors.initials: S
authors.lastname: Shiigi
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D000001:Calcimycin / Q000494:pharmacology; D002478:Cells, Cultured; D003000:Clonidine / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D007545:Isoproterenol / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects*; D013154:Spleen / Q000166:cytology* / Q000276:immunology; D013312:Stress, Physiological / Q000276:immunology / Q000503:physiopathology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014982:Xenopus laevis
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D000001:Calcimycin; D003907:Dexamethasone; D007545:Isoproterenol; D003000:Clonidine; D013755:Tetradecanoylphorbol Acetate