Comparison of airway obstruction induced by propranolol and YM-09538 (a combined alpha- and beta-adrenoceptor blocking drug).

In the isolated guinea-pig right atria and tracheal strips, both propranolol and YM-09538 caused a parallel shift of the dose-response curve for isoproterenol to the right, indicating that these two drugs block nonselectively the beta 1 1- and beta 2-adrenoceptors. Propranolol potentiated the histamine-induced bronchoconstriction in the anesthetized dogs, whereas YM-09538 did not affect the histamine-induced bronchoconstriction. Propranolol degranulated the isolated rat mesenteric mast cells in contrast to YM-09538 which had no significant effect on mast cells. Neither propranolol nor YM-09538 affected the hapten specific IgE antibody response in female BDF1 mice. These results suggest that YM-09538 has a much lesser effect on airway function than propranolol.