Effect of an Anti-SRS-A Agent, NZ-107, on Airway Responses Induced by Ovalbumin and A23187 in the Guinea-pig

Abstract

The effects of the anti-SRS-A agent NZ-107 on antigen-(ovalbumin) and calcium ionophore A23187-induced airway responses in the guinea-pig have been investigated. In the presence of 5 microM indomethacin, NZ-107 (3 microM) did not affect the peak response in ovalbumin-induced contraction but did inhibit the prolonged response following the peak response in the tracheal strip. A higher concentration of NZ-107 (10 microM) completely blocked both peak and prolonged responses. Inhibitory effects of NZ-107 on ovalbumin responses were less in the lung parenchymal strip. The potency of NZ-107 in inhibiting ovalbumin-induced tracheal contraction was not changed in the absence of indomethacin but was reduced in the presence of 45 mM serine-borate, an inhibitor of the conversion of LTC4 to LTD4. NZ-107 inhibited A23187-induced contractions in both tracheal and parenchymal strips but in both cases the inhibitory potency was less than that on ovalbumin response. NZ-107 was a more potent inhibitor of ovalbumin-induced SRS-A release than histamine release in lung fragments but was ineffective in inhibiting A23187-induced SRS-A and histamine release. NZ-107 at a concentration of 10 microM more effectively inhibited LTC4- and histamine-induced tracheal contractions than it did LTC4 in the presence of 45 mM serine-borate. These results suggest that NZ-107 selectively inhibits antigen-induced SRS-A responses in airway tissues of the guinea-pig.