Anaphylactic bronchoconstriction in BP2 mice: interactions between serotonin and acetylcholine

1 Immunized BP2 mice developed an acute bronchoconstriction in viva and air way muscle contraction in vitro in response to ovalbumin (OA) and these con tractions were dose dependent. 2 Methysergide or atropine inhibited OA-induced bronchoconstriction in vivo and airway muscle contraction in vitro. 3 Neostigmine potentiated the OA-induced bronchoconstriction in vivo and ai rway muscle contraction in vitro of BP2 mice. This potentiation was markedl y reduced by the administration of methysergide or atropine and when the tw o antagonists were administered together, the responses were completely inh ibited. 4 Neostigmine also potentiated the serotonin (5-HT)- and acetylcholine (ACh )-induced bronchoconstriction and this potentiation was significantly rever sed by atropine. 5 These results indicate that OA provokes a bronchoconstriction in immunize d BP2 mice by stimulating the release of 5-HT, which in turn acts via the c holinergic mediator, ACh.