Acetylcholine constrictor effect enhanced by hydrogen peroxide in ovalbumin-sensitised rat tracheal muscle

Ten Sprague-Dawley male rats were sensitised with ovalbumin. The effect of hydrogen peroxide on the constrictor effect of acetylcholine was studied in the isolated tracheal muscle. Preincubation with hydrogen peroxide (H2O2) 10(-3) M (1 min/30 min) does not modify the acetylcholine constrictor effect in the control group. Ovalbumin sensitisation enhanced the acetylcholine constrictor effect (mean value of 19%) irrespective of dosage, comparatively with the control group. Short- and long-term preincubation with hydrogen peroxide enhanced the acetylcholine effect in the sensitised group, irrespective of dosage, comparatively with the control group. A relationship between dosage, contractile response and time of incubation was noticed only in the sensitised group.