| Abstrakt: |
The effect of epithelium removal on the sensitivity of smooth muscle to carbachol and leukotriene D (LTD) was investigated in guinea-pig isolated tracheal preparations untreated and treated with a cyclooxygenase inhibitor, flurbiprofen (1 μol/1). The pD value of carbachol was not changed by epithelium removal or by flurbiprofen-treatment, alone or in combination. On the other hand, the pD of LTD was higher in the tracheal strips without epithelium than in the intact preparations. In preparations devoid of epithelium, the pD value of LTD was decreased by treatment with flurbiprofen, suggesting that the sensitivity of the smooth muscle (namely, epithelium-free preparations) to LTD is enhanced by intramurally produced excitatory prostaglandin(s) [PG(s)]. However, in intact preparations with epithelium, no such sensitized response to LTD was observed. After flurbiprofen-treatment, in the continued presence of prostaglandin F (PGF, 200 nmol/l), the sensitivity to LTD was partially recovered in the epithelium-free preparations, but not in the intact ones. These results suggest that epithelium diminishes the sensitizing effect of intramural excitatory PG(s) on responsiveness of tracheal smooth muscle to LTD4, possible via a non-prostanoid substance(s). [ABSTRACT FROM AUTHOR] |
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