Interaction between amphetamine and alpha 2-postsynaptic adrenoreceptors in the rat submaxillary gland.
1 The interaction between amphetamine and the alpha 2-adrenoreceptor agonists, clonidine and guanabenz, was studied in the submaxillary gland of anaesthetised rats. 2 Low doses of clonidine (10 micrograms/kg) and guanabenz (10 micrograms/kg) inhibited the secretory responses induced by methacholine and substance P, respectively. 3 Amphetamine (300 micrograms/kg) antagonized the inhibitory effects of both alpha 2-agonists. This dose of amphetamine alone did not show sialagogic effects. 4 Atropine (1 micrograms/kg) diminished the secretory responses to methacholine as much as clonidine (10 micrograms/kg). Amphetamine did not modify the blockade by atropine. 5 Guanabenz (10 micrograms/kg) markedly decreased the secretory responses to substance P, an effect that was also prevented by amphetamine. 6 Reserpine pretreatment (5 mg/kg, i.p., 18 h) did not alter the effect of amphetamine. 7 These results indicate that the interaction between amphetamine and alpha 2-adrenoreceptor agonists is unrelated to the indirect effect of this amine and suggest a direct interaction between the drug and postsynaptic inhibitory alpha 2-adrenoreceptors.
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D013363:Submandibular Gland / Q000187:drug effects* / Q000378:metabolism
D000316:Adrenergic alpha-Agonists; D011942:Receptors, Adrenergic, alpha; D000661:Amphetamine