Failure of 3-methylindole to contract the bovine pulmonary vein or to release mediators of anaphylaxis from the bovine lung in vitro

Strips of smooth muscle from the pulmonary vein, pulmonary artery, trachea and bronchus of calves were incubated in an organ bath with 3-methylindole (3MI) and 3-methyloxindole (3MOI). 3MI and 3MOI (5-640 micrograms/ml) did not cause contraction of any of the isolated smooth muscle preparations. No evidence for the release of mediators of anaphylaxis was obtained when chopped bovine lung preparations were incubated with 3MI (20 micrograms/ml) and 3MOI (25 micrograms/ml). Results of the present work diminish the possibility that the pneumotoxic effect of 3MI is due to a primary hydrodynamic imbalance across the alveolocapillary membrane resulting in excess filtration over reabsorption.