| Abstract: | 1. Responses to (+/-)-isoprenaline (Iso), (-)-adrenaline (Adr) and (-)-noradrenaline (NA) were compared in isolated preparations of human and porcine lung parenchyma strip. 2. The order of relaxant potencies of these catecholamines in both human and porcine lung parenchyma was Iso greater than Adr greater than NA (1:0.24:0.01, human; 1:0.21:0.01.pig). These results suggest that beta 2-adrenoceptors predominate in both types of lung parenchyma strip. 3. pA2 values for the beta-adrenoceptor antagonist, propranolol (non-selective), with Iso as the agonist, in human and porcine lung strips were 7.84 and 7.83 respectively and for atenolol were 6.50 and 5.35 respectively. Taken as a whole results indicate the existence of an apparently homogeneous population of beta 2-adrenoceptors in porcine parenchyma strip, while both beta 1 and beta 2-adrenoceptors were revealed in human lung parenchyma. |
