GALANIN AND SOMATOSTATIN INHIBITION OF NEUROKININ-A AND NEUROKININ-B INDUCED AIRWAY MUCUS SECRETION IN THE RAT

Neurokinin A and B are present in neurons situated in lung and NK-1 re ceptors have been described on tracheal submucosal gland cells. In the present study we compared the ability of substance P (SP), neurokinin A (NKA) and neurokinin B (NKB) to stimulate airway mucus secretion. F urthermore, we characterized the interaction of NKA and NKB with galan in and somatostatin. The rank order of the tachykinins to stimulate ai rway mucus secretion was SP > NKA > NKB suggesting that NK-1 receptors mediate these effects(EC(50):SP: 50 nmol/l, NKA: 200 nmol/l, NKB: 400 nmol/l). Galanin and somatostatin were equally potent to inhibit NK-A and NK-B stimulated airway mucus release. These results suggest that NK-A and NK-B are potent stimulators of airway macromolecule secretion . Galanin and somatostatin potently inhibit these actions of the tachy kinins. Therefore, airway mucus secretion is controlled by a complex n etwork of several different mediators.