Abstract
The airway epithelium is responsible for the production of a number of arachidonic acid and nonprostanoid inhibitory factors. Epithelium synthesises nitric oxide (NO) which may be important in regulating the function of airways smooth muscles. We studied in vitro the effect of histamine (100 nM100 μ M) which increases the NO release on rabbit airway smooth muscles induced by 80 mM KCl in the presence or not of 10-5 Methylene blue (MB) (inactivator of guanylate cyclase) or N(G)-monomethyl L-arginine (L-NMMA), a NOS inhibitor. All experiments were done in tracheal muscle strips from 28 rabbits with epithelium and after epithelium removal. The additional use of histamine (1 μ M) on KCl contraction induced a relaxation of 10% of the initial contraction. The additional use of L-NMMA decreased the relaxation to 5% of initial contraction. MB rather than L-NMMA increased the contraction significantly