Inhibitory effect of a peptide leukotriene antagonist ONO-1078 on LTD4- and antigen-induced thromboxane B2 production in guinea pig lungs.

The effect of a peptide leukotriene receptor antagonist ONO-1078 on the production of thromboxane (Tx) B2 induced by leukotriene (LT) D4 and antigen challenge was examined in guinea pig lungs. LTD4 (1-1,000 nM) induced a concentration-dependent production of TxB2 in non-sensitized guinea pig lungs and ovalbumin challenge (0.01-100 micrograms/ml) produced TxB2 and peptide leukotrienes in a concentration-dependent manner in ovalbumin-sensitized guinea pig lungs. ONO-1078 inhibited LTD4 (100 nM)-induced TxB2 production with the IC50 value of 0.24 microM. Furthermore, ONO-1078 inhibited antigen (10 micrograms/ml)-induced TxB2 production with the IC50 value of 0.14 microM without effect on the production of peptide leukotrienes. These results suggest that ONO-1078 may prevent the antigen-induced production of TxB2 through the blockade of the activation of receptors by endogenously generated peptide leukotrienes.