title: Alpha 2-adrenoceptor-mediated inhibition of platelet adenylate cyclase activity in heroin addicts in abstinence.
abstract: The inhibition of basal and forskolin-stimulated platelet adenylate cyclase activity by (-)adrenaline was studied in ten heroin addicts during spontaneous withdrawal. Both basal and forskolin-stimulated enzyme activities were increased during heroin withdrawal and the inhibitory effect induced by (-)adrenaline was potentiated with parallel shifts to the left of the concentration-effect curves. The number of binding sites for [3H](-)adrenaline in platelet membranes was also increased during withdrawal. Treatment with clonidine markedly attenuated the inhibitory effect induced by (-)adrenaline on platelet adenylate cyclase activity. The results indicate that the heroin withdrawal syndrome induces supersensitivity of the platelet alpha 2-adrenoceptor-adenylate cyclase system.
authors.forename: J A
authors.initials: JA
authors.lastname: García-Sevilla
authors.forename: I
authors.initials: I
authors.lastname: Ulibarri
authors.forename: L
authors.initials: L
authors.lastname: Ugedo
authors.forename: M
authors.initials: M
authors.lastname: Gutierrez
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000328:Adult; D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology*; D003000:Clonidine / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D005260:Female; D006556:Heroin Dependence / Q000201:enzymology* / Q000534:rehabilitation; D006801:Humans; D008297:Male; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000378:metabolism*; D013375:Substance Withdrawal Syndrome / Q000201:enzymology* / Q000534:rehabilitation
chemical_list: D011942:Receptors, Adrenergic, alpha; D000262:Adenylyl Cyclases; D003000:Clonidine