title: Heterogeneity of the interaction between alpha 1- and alpha 2-adrenoceptor agonists with their respective receptors in the vascular system of the pithed rat.
abstract: The subdivision of alpha 1- and alpha 2-adrenoceptor-mediated pressor responses to different agonists based upon the influence of beta 2-adrenoceptor-mediated vasodilatation was further investigated in the pithed normotensive rat. The effect of salbutamol (4.18 X 10(-6) mol/kg) on the alpha 1-adrenoceptor-mediated increase in diastolic pressure due to dopamine and amidephrine as well as on the alpha 2-adrenoceptor-mediated pressor response to azepexole, DP-6,7-ADTN, M-7, TL-99 and dopamine was assessed. The alpha 1-pressor responses to amidephrine and dopamine were only slightly attenuated by salbutamol. The alpha 2-adrenoceptor-mediated increase in diastolic pressure due to B-HT 933 was strongly antagonized by salbutamol in contrast to the effect of dopamine, DP-6,7-ADTN and M-7. TL-99 occupied in intermediate position. The data do not support the existence of distinctly different subtypes of alpha 1- and alpha 2-adrenoceptors but favor the hypothesis that both alpha 1- and alpha 2-adrenoceptors are activated in a unique way by each of their respective agonists.
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000145:classification / Q000494:pharmacology*; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D003042:Cocaine / Q000494:pharmacology; D004298:Dopamine / Q000494:pharmacology; D004558:Electric Stimulation; D004639:Emetics / Q000494:pharmacology; D004983:Ethanolamines / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects*; D008297:Male; D009284:Naphthols / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011412:Propanolamines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D013764:Tetrahydronaphthalenes / Q000494:pharmacology; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D000316:Adrenergic alpha-Agonists; D001381:Azepines; D004639:Emetics; D004983:Ethanolamines; D009284:Naphthols; D011412:Propanolamines; D011942:Receptors, Adrenergic, alpha; D013764:Tetrahydronaphthalenes; D015016:Yohimbine; C009957:5,6-dihydroxy-2-dimethylaminotetralin; C026777:ICI 118551; C016893:2-(N,N-dimethylamino)-6,7-dihydroxytetralin; C016980:amidephrine; C015603:azepexole; D003042:Cocaine; D004298:Dopamine; D011224:Prazosin