L’esposizione a persolfato d’ammonio riduce il controllo non adrenergico, non colinergico inibitorio (NANC-i) nelle vie aeree di cavia

To evaluate the effect of repeated exposure to ammonium persulphate (AP) on NANC inhibitory innervation of guinea-pig airways, we exposed male guinea-pigs to AP, by aerosol inhalation at a concentration of 1 mg/m3 for 30 minutes for 5 days for three weeks. Control animals inhaled saline aerosol. After the last exposure, the animals were killed and the isolated whole trachea was cannulated at each extremity and mounted in an organ bath. Intraluminal pressure variations were measured by means of a pressure transducer. The inhibitory NANC responses to electrical field stimulation (3 and 10 Hz) were evaluated in the presence of hyoscine, piperoxane and propranolol. To evaluate both the amplitude and the duration of the responses, the area under the curve (AUC) was measured as Pa · seconds. Statistical analysis, was performed by analysis of variance. In the exposed animals, the in vitro NANC relaxations at 3 and 10 Hz were significantly reduced (P < 0.01). In particular, the AUC was 45.9 ± 12.1%, as compared to control at 3 Hz and 52.7 ± 14.1% at 10 Hz. In conclusion, the impairment in NANC relaxation may represent one of the mechanisms subserving airway hyperreactivity induced by AP esposure.