Human lung adrenoreceptors studied by radioligand binding

1. Direct radioligand-binding techniques have been used to characterize and quantify adrenoreceptors in human peripheral lung tissue removed at thoracotomy from ten patients, nine of whom had evidence of obstructive airways disease. 2. [3H]Dihydroalprenolol was used to characterize beta-adrenoreceptor sites and [3H]prazosin to identify alpha-adrenoreceptor sites. Binding of both ligands showed saturability, high affinity, rapid kinetics, reversibility and stereospecificity. The rank order of agonists and antagonists inhibiting specific binding correlated well with known physiological potencies. Specificity of [3H]dihydroalprenolol binding suggested that the population of lung beta-adrenoreceptors is predominantly of the beta 2 subtype.