The influence of leukotrienes C4 and D4 on the contractility of an inflamed porcine uterus

The effect of leukotriene (LT) C4 (LTC4) and LTD4 on the contractility of an inflamed porcine uterus was investigated. On Day 3 of the estrous cycle (Day 0 of the study), either saline or Escherichia coli suspension was injected into each uterine horn. Although acute endometritis developed in all bacteria-inoculated gilts, a severe acute endometritis was noted more often on Day 8 than on Day 16. Myometrial and endometrial/myometrial strips were incubated with LTC4 or LTD4 alone, or together with a cysteinyl-LT receptor antagonist (BAY-u9773). Leukotriene C4 increased the contraction intensity in the saline- and bacteria-treated uteri on Day 8; however, its effect was lower in the myometrium of inflamed uteri. Contraction frequency was found to decrease in the saline-treated uteri as opposed to inflamed ones, in which it was elevated. On Day 16, contraction intensity increased in response to LTC4 in the saline-treated uteri but was reduced in the inflamed organs. The value of this parameter was lower in the inflamed uteri than that in the saline-treated ones. Leukotriene D4 (Days 8 and 16) augmented contractility in the saline-treated uteri, but despite increasing its intensity in the inflamed organs, it decreased contraction frequency. Leukotriene C4 or LTD4, added to BAY-u9773–pretreated saline- and bacteria-treated uteri on both days, decreased the contraction intensity. On Day 16 after treatment with BAY-u9773 and LTC4, contraction intensity in the endometrium/myometrium of the inflamed uteri was lower than that in the saline-treated organs. Data show that both LTC4 and LTD4 affect the contractility of inflamed porcine uteri, though LTC4 exerts a weaker contractile effect.