Supersensitivity to catecholamines after inhibition of extraneuronal uptake (uptake2) or O-methylation.
The influence of inhibition of uptake2 and of O-methylation on beta-adrenoceptor-mediated responses of guinea-pig trachea and rat uterus to some catecholamines was compared. The responses were more markedly enhanced by inhibition of O-methylation (by U-0521) than by inhibition of uptake2 (by hydrocortisone). The ranking order for the degree of super-sensitivity caused by either U-0521 or hydrocortisone was different in the two tissues, suggesting differences between the O-methylating systems of those tissues. In experiments with 3H-isoprenaline metabolism, hydrocortisone had a weak inhibitory effect on O-methylation in both tissues.
Proença
J
J
Department of Pharmacology, Faculty of Pharmacy, University of Porto, Portugal.
Paiva
M Q
MQ
Guimarães
S
S
D000818:Animals; D002395:Catecholamines / Q000378:metabolism / Q000494:pharmacology*; D005260:Female; D006168:Guinea Pigs; D006854:Hydrocortisone / Q000494:pharmacology; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000378:metabolism; D008745:Methylation; D011427:Propiophenones / Q000494:pharmacology; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism; D014132:Trachea / Q000187:drug effects / Q000378:metabolism; D014590:Uterine Contraction / Q000187:drug effects
D002395:Catecholamines; D011427:Propiophenones; D011943:Receptors, Adrenergic, beta; C006104:U 0521; D007545:Isoproterenol; D006854:Hydrocortisone