Separation of the two components of the contractile activity of leukotriene C4 on the guinea pig lung parenchymal strip.

The contractions, induced by LTC4 in the guinea pig lung parenchymal strip are composed of two parts, one of which is due to the effect of the released TxA2 and the other one to the direct action of LTC4. After the addition of indomethacin, the TxA2 release is totally inhibited, but the contractions only partly. It is shown that the release of TxA2 only occurs during the initial period of the contractions. This indicates that the direct action of LTC4 represents the slow acting component in the contraction.