In vitro effects of hydrogen peroxide on rat uterine contraction before and during pregnancy

AIM: To assess the in vitro effect of hydrogen peroxide (H(2)O(2)) on uterine contractions in pregnant and non-pregnant rats. METHODS: The study was performed at the Department of Physiology, College of Medicine, King Saud University from December 2016 to October 2017. Intact uterine samples were obtained from non-pregnant (n = 7-8) and term-pregnant (n = 6-7) rats. Small longitudinal uterine strips were dissected and mounted in an organ bath. Isometric force measurements were used to assess the effect of 400, 800, and 1000 μM H(2)O(2) on spontaneous uterine contractions and contractions induced by oxytocin (5 nM), high calcium (Ca(+2)) solution (6 mmol/L), and high potassium chloride (KCl) solution (60 mmol/L). RESULTS: In both term-pregnant and non-pregnant uterine strips, H(2)O(2) elicited a biphasic response, consisting of a transient contraction followed by a persistent decrease in spontaneously generated contractions, contractions induced by oxytocin, and contractions induced by high Ca(+2) (all P < 0.01, compared with controls) in a concentration-dependent manner. The effect of H(2)O(2) was more pronounced in non-pregnant than in pregnant rats (P < 0.05). In both groups, H(2)O(2) failed to relax uterine strips pre-contracted with high-KCl solution (P > 0.05 compared with controls). CONCLUSION: H(2)O(2) was shown to be a potent uterine relaxant in pregnant and non-pregnant states. The pregnant uterus better withstood the inhibitory effect of H(2)O(2) than non-pregnant uterus.