Interaction between nitric oxide and prostanoids in the respiratory system

Prostaglandins and nitric oxide are important mediators of different physiological and pathophysiological processes. So far, is not characterized clearly their relationship in the conditions of airways hyperreactivity.

We tried to detect the relationship of interaction NOS-COX in conditions of exogenous irritant-induced experimental bronchial hyperreactivity.

Male guinea pigs were used in the experiment. Animals received agent that inhibits COX activity--diclofenac in a dose of 10 mg/kg i.m. or direct NO donor--molsidomine in a dose of 2 mg/kg i.p. Agents were administered singly (10 days) or in combination (last 3 days). Then animals were exposed to the toluene vapours for two hours over each of three consecutive days to provoke hyperreactivity. Then we recorded the reactivity changes to cumulative doses of histamine or acetylcholine (10(-8)-10(-3) mol/I).

The administration of NO donor (10 days) and consecutive COX inhibition (3 days) increased the reactivity of both observed preparations in comparison to agents administered single. COX inhibition during 10 days and consecutive treatment with NO donor (3 days) evoked different changes of tracheal smooth muscle and lung tissue smooth muscle response but had more beneficial effect on the airways reactivity on the whole.

It is possible to suppose some participation of both followed enzymatic systems and theirs interaction in our experimental conditions since airways reactivity was affected the by used agents (Fig. 7, Ref. 32).