Epithelial prostaglandins’ role in rats’ smooth muscle contraction of trachea and bronchi

The article considers the role of epithelial prostaglandins of lower respiratory tract of rats in contractile activity of smooth muscles of trachea and bronchi. Studies were conducted on isolated preparations with the use of electrical stimulations of postganglionic nerves (frequency - 30 stimuli, duration - 0,5 ms, amplitude - 20 V, duration of stimulation - 10 s). It was revealed that epithelial prostaglandins increase contractile activity of smooth muscles. In the study, we used adenosine and capsaicin as experimental analogues of the external environmental factors. Bronchoconstriction effects of adenosine persisted in spite of the inhibition of prostaglandin synthesis. Contractile activity of capsaicin was preserved only in the preparations with ganglia. The relaxation of muscles was observed in preparations without ganglia. It is probable that the influence of capsaicin epithelial prostaglandins decreases the activity of tachykinins C-fibers responsible for bronchoconstriction. At the same time, reduction of the smooth muscle contractions in preparations without ganglia may speak of the role played by the intramural nerve structures in the constricting effect mediated by the activation of C-fibers.