Cardiovascular effects of 2-Br-alpha-ergocriptine in urethane anesthetized rats.
Experiments were designed to study the cardiovascular effects of Bromocriptine (2-Br-alpha-ergocriptine) in the normotensive anesthetized rats. The intravenous administration of bromocriptine (20 micrograms/kg and 200 micrograms/kg) produced a long-lasting and not dose-dependent fall in the mean blood pressure and heart rate. The pressor response to phenylephrine, an alpha adrenergic agonist, was antagonized by bromocriptine in a dose-dependent manner. At a dose of 20 micrograms/kg bromocriptine behaved as a competitive antagonist, whereas at the dose of 200 micrograms/kg produced an insurmountable blockade of the response to phenylephrine. Previous administration of phentolamine (5 mg/kg) prevented the insurmountable blockade of alpha adrenoceptors by bromocriptine. This observation suggests that both drugs compete for the same receptor. It is concluded that blockade of peripheral alpha-adrenoceptors may contribute to cardiovascular effects of bromocriptine.
D000758:Anesthesia; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001971:Bromocriptine / Q000008:administration & dosage / Q000494:pharmacology*; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D010646:Phentolamine / Q000494:pharmacology; D010656:Phenylephrine / Q000037:antagonists & inhibitors; D051381:Rats; D011919:Rats, Inbred Strains; D014520:Urethane
D010656:Phenylephrine; D001971:Bromocriptine; D014520:Urethane; D010646:Phentolamine