Fig. 1. Dose–response curves for noradrenaline (open squares, N=7) and phenylephrine (filled squares, N=11) in quiescent cells of the venom gland of Bothrops jararaca, as assessed by microphysiometry. Cultured cells were perfused with the agonists for 1 min, a complete dose–reponse curve was constructed in each well, and the interval between successive doses was 30 min. All experiments were done in the presence of the ß-adrenoceptor blocker propranolol. Values are means ± S.E.M.