title: Effect of steroids on beta-adrenoceptor-mediated relaxation of pig bronchus.
abstract: 1--Progesterone, testosterone (40 microM), cortisol and cortisol hemisuccinate (80 microM) caused 6-8 fold potentiations of (+/-)-isoprenaline (Iso)-induced relaxations of pig bronchus while several other steroids caused smaller potentiations or had no effect. 2--17 beta-Oestradiol (40 microM) increased the potency of Iso, (-)-adrenaline (Adr) and (-)-noradrenaline (NA) by 10.6, 2.3 and 2.6 fold respectively but had no significant effect on the potency of fenoterol (Fen). 3--Inhibition of catechol-O-methyl transferase (COMT) with U-0521 (30 microM) caused a 6 fold increase in the potency of Iso but failed to alter the potency of Adr, NA or Fen. The extraneuronal uptake inhibitor normetanephrine (50 microM) caused significant 2 fold increases in the potency of Iso and Adr but did not potentiate the responses to NA or Fen. 4--In preparations where the potency of Iso had already been increased by U-0521 (30 microM) or by normetanephrine, 17 beta-oestradiol produced no significant further increase in potency. These results indicate that steroid-induced increases in the potency of catecholamines in pig bronchus can be explained in terms of inhibition of COMT or extraneuronal uptake or both.
mesh_terms: D000403:Airway Resistance / Q000187:drug effects*; D000818:Animals; D001980:Bronchi / Q000187:drug effects; D002395:Catecholamines / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D005280:Fenoterol / Q000494:pharmacology; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008745:Methylation; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D013256:Steroids / Q000494:pharmacology*; D013552:Swine; D013566:Sympathomimetics / Q000494:pharmacology
chemical_list: D002395:Catecholamines; D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D013256:Steroids; D013566:Sympathomimetics; D005280:Fenoterol; D004958:Estradiol; D007545:Isoproterenol