Hashimoto M, Hayashi K, Murai M, Fujii T, Nishikawa M, Kiyoto S, Okuhara M, Kohsaka M, Imanaka H
Exploratory Research Laboratories, Fujisawa Pharmaceutical Co., Ltd., Ibaraki, Japan.
J Antibiot (Tokyo). 1992 Jul;45(7):1064-70. doi: 10.7164/antibiotics.45.1064.
WS9326A binds competitively to [3H]substance P (NK-1 receptor) binding sites on guinea-pig lung membranes (IC50 = 3.6 x 10(-6) M), and acts as a tachykinin antagonist in various functional assays. WS9326A inhibited tracheal constrictions produced by exogenously added substance P and neurokinin A, with IC50 values of 9.7 x 10(-6) M and 3.5 x 10(-6) M, respectively. WS9326A inhibited neurokinin A-induced bronchoconstriction in a dose dependent manner when administered to guinea-pigs intravenously together with neurokinin A, and was also effective in preventing capsaicin-induced bronchoconstriction, which is known to be caused by release of endogenous tachykinins (substance P and neurokinin A). FK224 (tetrahydro-WS9326A; catalytic hydrogenation of WS9326A gave FK224) was more potent than WS9326A in the [3H]substance P receptor binding assay using guinea-pig lung membrane (IC50 = 1.0 x 10(-7) M).
