ANTIPEPTIDE ANTIBODIES SENSITIVE TO THE ACTIVE STATE OF THE BETA(2)-ADRENERGIC RECEPTOR

Antibodies directed against a peptide corresponding to the second loop of the human beta(2)-adrenergic receptor were induced in rabbits by i mmunisation with the free peptide in complete Freund's adjuvant. The r esulting antibodies were affinity-purified and shown to be monospecifi c for the target receptor. They were able to stimulate the L-type Ca2 channels in whole-cell patch-clamp experiments on isolated adult guin eapig cardiomyocytes. This effect was similar to that obtained by the specific beta(2)-adrenergic agonist zinterol. The antibody effects cou ld be blocked with the specific beta(2)-adrenergic inverse agonist ICI 118,551 but not with the neutral antagonist alprenolol. These results suggest that the antibodies recognise the active conformer of the beta (2)-adrenergic receptor.