title: Subclasses of beta-adrenoceptors--a quantitative estimation of beta 1- and beta 2- adrenoceptors in guinea pig and human lung.
abstract: Binding studies have been performed in guinea pig and human lung membranes with the radioligand ICYP and several 'cardioselective' beta-adrenoceptor antagonists. Analysis of data from displacement curves by means of a curve fitting procedure, based on a non-linear regression analysis, indicated that in both tissues beta 1- and beta 2-type adrenoceptors coexisted. The relative proportions of the two receptor subtypes in a single tissue remained constant, irrespective of the antagonist used. The percentage of distribution between beta 1- and beta 2-adrenoceptors was about 22:78 in the guinea pig lung and 30:70 in human lung. For the compounds investigated, the affinities of beta 1- and beta 2-adrenoceptors correlated highly significantly between both species, suggesting that the 'cardioselectivity ratio" of a compound is the same in the guinea pig and in man. Mathematical treatment of the displacement curves provided no evidence of a further class of beta-adrenoceptors in lungs of both species.
mesh_terms: D000368:Aged; D000818:Animals; D001262:Atenolol / Q000378:metabolism; D015784:Betaxolol; D002462:Cell Membrane / Q000032:analysis; D006168:Guinea Pigs; D006801:Humans; D020120:Iodocyanopindolol; D008168:Lung / Q000032:analysis*; D008790:Metoprolol / Q000378:metabolism; D008875:Middle Aged; D008954:Models, Biological; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism; D011217:Practolol / Q000378:metabolism; D011412:Propanolamines / Q000378:metabolism; D011941:Receptors, Adrenergic / Q000032:analysis*; D011943:Receptors, Adrenergic, beta / Q000032:analysis* / Q000378:metabolism
chemical_list: D011412:Propanolamines; D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D001262:Atenolol; D020120:Iodocyanopindolol; D010869:Pindolol; D008790:Metoprolol; D015784:Betaxolol; D011217:Practolol