NEDOCROMIL SODIUM MODULATES NONADRENERGIC, NONCHOLINERGIC BRONCHOCONSTRICTOR NERVES IN GUINEA-PIG AIRWAYS INVITRO

Nonadrenergic, noncholinergic (NANC) neural bronchoconstrictor responses in guinea pig airways are due to the release of tachykinins from sensory nerves. We have performed an in vitro study using electrical field stimulation (EFS; 40 V, 0.5 ms, 8 Hz for 20 s) in guinea pig bronchi to investigate the effect of nedocromil sodium (NS) on NANC bronchoconstrictor responses. NS inhibited NANC bronchoconstriction in bronchi in a concentration-dependent manner, with a maximum inhibition of 40 +/- 4% (p < 0.001, n = 6) at 100-mu-M. Cromolyn sodium, however, produced only 9 +/- 8% inhibition at the same molar concentration (p < 0.05). NS did not affect the contractile response to substance P, nor did it modulate the cholinergic bronchoconstrictor response to EFS in tracheal smooth muscle. These results indicate that NS may modulate the release of tachykinins from airway sensory nerves.