The effect of chopped rat lung on the inhibitory actions of prostaglandins, isoprenaline, theophylline and disodium cromoglycate on mast cell degranulation.

Prostaglandins and other drugs that stimulate adenylate cyclase have little inhibitory activity for antigen-induced degranulation of rat peritoneal mast cells. In the presence of chopped rat lung, however, the inhibitory activities of both prostaglandins and isoprenaline were markedly enhanced. A similar effect was also seen with disodium cromoglycate, which is not known to stimulate adenylate cyclase, but which does inhibit cyclic AMP phosphodiesterase. In contrast, however, the chopped lung had no effect on either degranulation in the absence of an inhibitor or on the inhibitory potency of theophylline. Lung tissue suspension pretreated with isoprenaline released a factor into the supernatant which enhanced isoprenaline action on peritoneal mast cells. The activity of this supernatant factor was destroyed by boiling for 5 min. Untreated lung supernatant fluid failed to affect either the level of antigen-induced degranulation or the inhibitory potency of isoprenaline.