[Role of nitric oxide in tachykinin-induced increase in Cl diffusion potential difference of rabbit tracheal mucosa]

To examine the effect of tachykinins on Cl secretion across tracheal mucosa and the possible contribution of nitric oxide (NO) formation to their actions in vivo, we measured Cl diffusion potential difference (Cl-PD) with a high-impedance voltmeter in the presence of amiloride. Superfusion of each neurokinin A (NKA) and substance P (SP) increased Cl-PD in a concentration-dependent fashion, whereas neurokinin B (NKB) had no effect, with the rank order of potency being NKA > SP >> NKB. The tachykinin-induced increase in Cl-PD was inhibited by the NO synthase inhibitor NG-nitro-L-arginine methylester (L-NAME), an effect that was reversed by L-arginine but not by D-arginine. These results suggest that tachykinins increase Cl secretion across rabbit trachea from the submucosa toward the lumen via stimulation of NK2 receptors and that NO formation may be involved in at least part of this process.