title: Further characterization of presynaptic beta-adrenoceptors in guinea-pig pulmonary arteries.
abstract: Presynaptic beta-adrenoceptors were further characterized in spiral strips of guinea-pig pulmonary arteries preloaded with [3H]norepinephrine. l-Metoprolol (3 X 10(-6) M) inhibited isoproterenol (3 X 10(-7) M)-induced increases in 3H efflux by transmural field stimulation, whereas the d-isomer produced no inhibition. However, IPS 339, H 35/25, butoxamine and metoprolol (3 X 10(-6) M) antagonized salbutamol (3 X 10(-7) M)-induced increases in the parameter, whereas acebutolol, bevantolol and practolol (3 X 10(-6) M) produced no antagonism. Presynaptic beta-adrenoceptors in guinea-pig pulmonary arteries appear to have characteristics similar to those postsynaptic classical beta-adrenoceptors.
mesh_terms: D000420:Albuterol / Q000494:pharmacology; D000818:Animals; D006168:Guinea Pigs; D008297:Male; D008790:Metoprolol / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism; D011651:Pulmonary Artery / Q000032:analysis* / Q000187:drug effects / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000032:analysis*
chemical_list: D011943:Receptors, Adrenergic, beta; D008790:Metoprolol; D000420:Albuterol; D009638:Norepinephrine