title: BRL 37344 inhibited adrenergic transmission in the rat portal vein via atypical beta-adrenoceptors.
abstract: The effect of BRL 37344, a beta(3)-adrenergic agonist on adrenergic transmission in isolated segments of the rat portal vein was examined in this study. BRL 37344 (10(-9) - 10(-5)M) produced concentration-dependent inhibition of electrically induced contractions. This inhibitory effect of BRL 37344 was not antagonized by propranolol ( 10(-6)M). Isoprenaline ( 10(-9) - 10(-4)M) also produced a concentration-dependent inhibition of electrically induced contractions in the portal vein. Propranolol (10(-6)M) antagonized isoprenaline responses with a -logK(B) value of 8.14 +/- 0.32. BRL 37344-induced inhibition of electrically induced contractions was also unaffected by cyanopindolol (10(-6)M). Isoprenaline but not BRL 37344 significantly reduced noradrenaline-induced contractions of the rat portal vein. CGP12177A produced propranolol-resistant inhibition of electrically induced contractions of the rat portal vein. It was therefore concluded that BRL 37344 inhibited adrenergic transmission in the rat portal vein via atypical beta -adrenoceptors located prejunctionally.
authors.affiliation: Department of Pharmacology & Toxicology, Faculty of Medicine, Kuwait University, P.O. Box 24923, Safat 13110, Kuwait. mariam@hsc.kuniv.edu.kw
authors.forename: Mariam H M
authors.initials: MH
authors.lastname: Yousif
authors.forename: Mabayoje A
authors.initials: MA
authors.lastname: Oriowo
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D004983:Ethanolamines / Q000494:pharmacology*; D005260:Female; D007545:Isoproterenol / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D011169:Portal Vein / Q000187:drug effects* / Q000294:innervation*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D013564:Sympathetic Nervous System / Q000187:drug effects*; D009435:Synaptic Transmission / Q000187:drug effects*
chemical_list: D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D004983:Ethanolamines; D011943:Receptors, Adrenergic, beta; C057368:BRL 37344; D007545:Isoproterenol; D009638:Norepinephrine