[Alteration of trachea and bronchi smooth muscles constriction under long inhalation of dioxide nitrogen by rats]

On insulated preparation of trachea and bronchi, change of the smooth muscles constriction was studied in rats inhaling dioxide nitrogen during 15, 30 and 60 days. The inhalation enhanced 1.5-fold and bronchi 2.5-fold responses of tracheal smooth muscles to stimulation of preganglionic nerve. The delay of the response in both events increased 1.3-fold. Long repeated stimulation caused a further increase of the constriction of tracheas and bronchi (1.32-fold). Blocking receptor with Novocain (1.0 mcg/ml) reduced the amplitude of the constriction and enhanced the response delay. After 30 days of inhalation, repeated nerve stimulations enhanced the amplitude of the constriction up to 120%, but after 60 days it reduced the amplitude of the constriction to 71 and 77% in preparations of tracheas and bronchi, respectively. In our opinion, long inhalation of dioxide nitrogen broke functioning of local lung nervous system controlling activity of the smooth muscles. The research results indicate important role of neuron functional module in pathology of the respiratory ways caused inhalation of dioxide nitrogen.