Effect of nonadrenergic noncholinergic inhibitory nerve stimulation on the allergic reaction in cat airways

To examine the effect of nonadrenergic noncholinergic (NANC) inhibitory nerve stimulation on the antigen inhalation with allergic animals, changes in pulmonary resistance (RL) and arterial plasma histamine concentration ([H]) caused by inhalation of Ascaris suum antigen were studied in five control (Group A) and five nerve-stimulated (Group B) cats, which were anesthetized and mechanically ventilated. All animals were actively sensitized with Ascaris antigen before the experiment. After cholinergic and beta-adrenergic blockade with intravenously administered atropine (3 mg/kg) and propranolol (2 mg/kg), inhalation of the antigen (1:100 dilution) was performed for 3 min. For Group B, bilateral cervical vagi were stimulated electrically for 1 min before the antigen inhalation and successively every 30 s until 5 min had passed from the onset of inhalation. RL and [H] were determined before, during, and after antigen inhalation in both groups. Baseline RL and [H] did not differ significantly between groups (16.3 +/- 2.2 (mean +/- SE) cm H2O/L/s and 14.0 +/- 0.7 ng/ml, respectively, for Group A; 14.4 +/- 1.3 and 15.6 +/- 2.7, respectively, for Group B). Increases in RL and [H] of Group B after the antigen inhalation were significantly depressed, compared with Group A (p less than 0.01 and p less than 0.05, respectively, two-way ANOVA). The increase in RL 5 min after antigen inhalation was 113 +/- 19% for Group A and 28 +/- 8% for Group B, and the increase in [H] at the same point was 36.3 +/- 9.1 ng/ml for Group A and 4.4 +/- 1.4 ng/ml for Group B.(ABSTRACT TRUNCATED AT 250 WORDS)