Am. J. Respir. Crit. Care Med., Vol 151, No. 3, 03 1995, 892-894.
Epithelial modulation of leukotriene-C4-induced human tracheal smooth muscle contraction
M Yamaya, K Sekizawa, K Yamauchi, H Hoshi, T Sawai and H Sasaki
Department of Geriatric Medicine, Tohoku University School of Medicine, Sendai, Japan.
We investigated the role of epithelium in smooth muscle contraction induced
by leukotriene C4 (LTC4) in isolated human trachea. The contractile
response to LTC4 was potentiated by a gamma-glutamyl transpeptidase
(gamma-GTP) inhibitor L-serine borate and by removal of the epithelium.
Both L-serine borate (4.5 x 10(-2) M) and removal of the epithelium shifted
the concentration-response curves to LTC4 to lower concentrations by 1.2
and 1.0 log units, respectively. Incubation of cultured human tracheal
epithelial cells with either LTC4 or LTD4 resulted in the formation of LTD4
or LTE4. The isolated epithelial cells and cultured epithelial cells
contained gamma-GTP activity. Histochemical study indicated that
gamma-GTP-like activity was present in the epithelial, submucosal, and
smooth muscle layers. These findings suggest that the epithelium modulates
the contractile response to LTC4 in human trachea by LT-degrading enzymes.