Effects of (+/-) dobutamine and its (+) and (-) enantiomers in the isolated rat portal vein.
Employing the isolated rat portal vein for testing (+/-) dobutamine, and its (+) and (-) enantiomers, we have confirmed the results obtained by Ruffolo et al (1981, 1983) using different methods. In the rat portal vein, (-) dobutamine acts as an alpha agonist, less potent than noradrenaline. The racemate acts as an alpha-agonist with about half the potency of (-) dobutamine. The (+) isomer shows no effects. In the presence of the alpha blocker BE 2254, all compounds, (+/-), (+) and (-) dobutamine, showed dose-dependent beta effects. These were surely the result of the action on beta 2 adrenoceptors since they could be antagonized by the potent and specific beta 2 antagonist ICI 118-551. We have found that (+) dobutamine is, as a beta 2 agonist, 355 to 1,480 times less potent than isoprenaline and 12-16 times more potent than (-) dobutamine. The pA2 of ICI 118-551 against (+) dobutamine is 9.36 (+/- 0.04). This high value is further proof that the beta receptor population of the rat portal vein is beta 2.
Vidal-Beretervide
K
K
Department of Pharmacology, School of Medicine, Hospital de Clinicas, Montevideo, Uruguay.
D000818:Animals; D004280:Dobutamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D011169:Portal Vein / Q000187:drug effects / Q000502:physiology; D011412:Propanolamines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects; D013237:Stereoisomerism; D014661:Vasoconstriction / Q000187:drug effects
D011412:Propanolamines; D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D004280:Dobutamine; C026777:ICI 118551