Propranolol induces hyperreactivity in lung parenchyma strips from sensitized guinea pigs

Propranolol causes airway hyperreactivity to agonists or antigenic challenge in vivo, but its mechanisms are still debated. In this study we found that the addition of propranolol (10 μ/ml) to lung parenchyma strips from sensitized guinea pigs enhanced the sensitivity and maximum contraction to antigenic challenge (ovalbumin, 0.01–100 μ/ml) and the sensitivity to histamine (1 × 10^?7 to 1.7 × 10^?4 M), determined through concentration-response curves. In contrast, tracheal chains from sensitized guinea pigs were unaffected. These results in in vitro preparations strongly suggest that, at least in lung parenchyma tissue, other mechanisms different from beta-blockade are present in propranolol-induced airway hyperreactivity.