Involvement of alpha 2-adrenoceptors and protein kinase C on nicotine-induced facilitation of noradrenaline release in bovine cerebral arteries.
1. Incubation of bovine cerebral vessels (previously exposed to [3H]-noradrenaline) with nicotine for 30 sec produced a facilitation of the electrically-induced noradrenaline release, which was antagonized by hexamethonium, a blocker of nicotinic receptors. This facilitation was not observed when the incubation time was increased to 20 or 75 min. 2. Rauwolscine, an alpha 2-adrenoceptor blocker, enhanced and phorbol 12, 13-dibutyrate reduced the facilitator effect produced by 30 sec exposure to nicotine. 3. These data suggest: (1) presynaptic nicotinic receptors produce a facilitation of stimulated noradrenaline release; these receptors are easily desensitized by increasing the incubation time with nicotine; (2) protein kinase C and alpha 2-adrenoceptors appear to be involved in this process.
Sánchez-Merino
J A
JA
Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma, Madrid, Spain.
Marín
J
J
Balfagón
G
G
Ferrer
M
M
D058647:Adrenergic alpha-2 Receptor Agonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D002417:Cattle; D002536:Cerebral Arteries / Q000187:drug effects / Q000378:metabolism*; D004558:Electric Stimulation; D018738:Hexamethonium / Q000494:pharmacology; D066298:In Vitro Techniques; D009411:Nerve Endings / Q000187:drug effects / Q000378:metabolism; D009538:Nicotine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009638:Norepinephrine / Q000378:metabolism*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism*; D011978:Receptors, Nicotinic / Q000187:drug effects / Q000378:metabolism; D017661:Receptors, Presynaptic / Q000187:drug effects / Q000378:metabolism; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000378:metabolism; D015016:Yohimbine / Q000494:pharmacology
D058647:Adrenergic alpha-2 Receptor Agonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D000316:Adrenergic alpha-Agonists; D001381:Azepines; D018341:Receptors, Adrenergic, alpha-2; D011978:Receptors, Nicotinic; D017661:Receptors, Presynaptic; D015016:Yohimbine; D015240:Phorbol 12,13-Dibutyrate; D018738:Hexamethonium; D009538:Nicotine; C024763:talipexole; D011493:Protein Kinase C; D009638:Norepinephrine