Figure 1
LTB 4 attenuates the antigen-induced asthmatic response in guinea pigs, and U75302 blocks the inhibitory effect of LTB 4 . Animals were challenged for 30 s with aerosolized 1% ovalbumin and Penh values were measured before and 1, 2, 3, 4, 5, 10 and 15 min after the antigen challenge on day 21 after ovalbumin sensitization. Vehicle, LTB4 or U75302 was administered via i.c.v. before antigen challenge. Penh values are expressed as the percent change from baseline. A: LTB4 or U75302 i.c.v. did not increase the Penh value in saline-sensitized control guinea pigs. B: The antigen challenge-induced increase in Penh value was dose-dependently suppressed by LTB4 i.c.v. in ovalbumin-sensitized guinea pigs. C: U75302 100 ng i.c.v. pretreatment completely blocked the inhibitory effects of LTB4 on antigen-induced increases in airway resistance. Data are expressed as mean ± S.E.M. (n = 8 per group). #P < 0.05, ##P  0.01 vs. NS-vehicle group; *P < 0.05, **P < 0.01 vs. OVA-vehicle group; †P < 0.05, ††P < 0.01 vs. OVA-LTB4 30 ng group. OVA, ovalbumin; NS, saline.