Endotoxin, interleukin-1β interleukin-6, or tumor necrosis factor-α do not acutely stimulate isolated murine myometrial contractile activity

OBJECTIVES: Endotoxin, interleukin-1β, interleukin-6, and tumor necrosis factor-α have been implicated in the pathogenesis of preterm labor, but their acute effect on myometrial contractile activity is unknown. The objective of this study was to determine their effect on isolated pregnant murine myometrial contractile activity. STUDY DESIGN: Isometric contractions were measured in myometrium isolated from pregnancy day 18 Swiss-Webster mice. Frequency, duration, amplitude, and integrated area were compared before and after the addition of endotoxin (10³ and 10⁴ ng/ml) (n = 6), interleukin-1β (10 and 10 ng/ml) (n = 6), interleukin-6 (1 and 10 ng/ml) (n = 6), and tumor necrosis factor-α (1 and 10 ng/ml) (n = 6). Results were analyzed with the Wilcoxon rank-sum test. RESULTS: The addition of endotoxin, interleukin-1β, interleukin-6, or tumor necrosis factor-α did not result in a change in the contractile activity of isolated pregnant murine myometrium compared with control. CONCLUSION: Endotoxin, interleukin-1β interleukin-6, and tumor necrosis factor-α do not acutely increase isolated murine myometrial contractile activity.