Jpn J Pharmacol. 1995 Sep; 69(1): 29-35.

Effect of saiboku-to, an antiasthmatic herbal medicine, on nitric oxide generation from cultured canine airway epithelial cells.

Tamaoki J, Kondo M, Chiyotani A, Takemura H, Konno K.

First Department of Medicine, Tokyo Women's Medical College, Japan.

The effect of Saiboku-to (TJ-96), an antiasthmatic Kampo medicine, on the generation of nitric oxide (NO) from cultured canine tracheal epithelium was investigated using a highly specific amperometric sensor for this molecule in vitro. Immersion of the NO-selective electrode in the medium containing tracheal epithelial cells detected the baseline current of 16.8-57.0 pA, which corresponded to an NO concentration ([NO]) of 39.7 +/- 8.1 nM. Addition of TJ-96 increased [NO] in a concentration-dependent manner, the maximal increase from the baseline level and the concentration of TJ-96 required to produce a half-maximal effect (EC50) being 127.5 +/- 20.1 nM (P < 0.001) and 86 +/- 9 micrograms/ml, respectively. Pretreatment of cells with NG-nitro-L-arginine methylester (L-NAME) greatly inhibited the TJ-96-induced increase in [NO], whereas NG-nitro-D-arginine methylester (D-NAME) had no effect, and this inhibition was reversed by L-arginine but not by D-arginine. Cytochemical staining of the epithelial cells showed marked reactivity of NADPH diaphorase activity. These results suggest that NO is spontaneously released by the airway epithelium and that TJ-96 stimulates the epithelial NO generation.