Effects of beta-agonist and antagonist on the pulmonary circulation and the pulmonary pressor response to 5-HT.
We investigated the effects of beta-agonist and antagonist (isoproterenol, propranolol) on the pulmonary circulation and on the pulmonary pressor response to 5-HT in an isolated canine lung lobe. The pulmonary vessels were dilated by isoproterenol at doses up to 200 micrograms, but were constricted by alpha-adrenoceptor stimulation at relatively high doses. The mechanism by which isoproterenol inhibited the 5-HT response is probably related to the stimulation of beta-adrenoceptors at the lower doses and to the stimulation of alpha-adrenoceptors at the higher doses. Propranolol alone had no effect on pulmonary vascular tone, but inhibited the 5-HT response markedly at doses high, possibly by directly blocking the 5-HT receptors.
Takashio
T
T
First Department of Internal Medicine, Asahikawa Medical College, Hokkaido, Japan.
Yamashita
H
H
Onodera
S
S
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000187:drug effects*; D004285:Dogs; D007545:Isoproterenol / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011652:Pulmonary Circulation / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology*; D014655:Vascular Resistance / Q000187:drug effects
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D012701:Serotonin; D011433:Propranolol; D007545:Isoproterenol