| Abstract: | The functional state of rat's airway smooth muscle was not changed after nitrogen dioxide inhalation for 30 days. The smooth muscle contraction increased only at second stimulation of preganglionic nervous fibers. Removal of mucosa or Novocain blockade of receptors decreased control smooth contraction at nerve and muscle fiber stimulation but the repeated stimulation of nerve increased the muscle contraction. The processing of trachea and bronchus preparations by prednisolon (1-10 microg/ml) decreased muscle reactions to 12% only at nerve stimulation. Prednisolon didn't change reactions of preparations with removed or blockaded receptors induced by nerve stimulation, but prednisolon (10 microg/ml) increased contraction at muscle stimulation. The relax effect of prednisolon on airway smooth muscle realizes via tracheobronchial receptors. High doses of prednisolon may direct effect on muscle increasing its contraction. |
