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Melatonin inhibits vasopastic action of hydrogen peroxide in human umbilical artery
Author(s) -
Okatani Yuji,
Watanabe Kazushi,
Hayashi Kazutoshi,
Wakatsuki Akihiko,
Sagara Yusuke
Publication year - 1997
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/j.1600-079x.1997.tb00318.x
Subject(s) - melatonin , catalase , hydrogen peroxide , nitric oxide , mannitol , endocrinology , medicine , antioxidant , chemistry , sodium nitroprusside , umbilical artery , biochemistry , biology , gestation , pregnancy , genetics
We evaluated the antioxidant property of melatonin as it relates to the vasospastic effect of hydrogen peroxide (H 2 O 2 ) on the human umbilical artery. Helical sections of umbilical arteries were obtained from healthy pregnant women who were delivered between weeks 37 and 39 of gestation. Changes in maximal potassium chloride (KCl)‐induced tension were measured in arterial segments with intact endothelium. Segments were treated with H 2 O 2 alone, or were pretreated either with an H 2 O 2 scavenger (catalase, 2000 IU), a hydroxyl radical scavenger (mannitol, 10 −2 M), a nitric oxide‐synthesis inhibitor (L‐N G ‐monomethyl arginine, LNMA, 2 × 10 −4 M), or melatonin (10 −6 M to 10 −4 M). The effect of H 2 O 2 (10 −4 M) on the relaxation induced by the calcium ionophore A23187 was also determined in arterial segments, with or without pretreatment with melatonin (10 −6 M, 10 −4 M). H 2 O 2 (10 −6 M to 10 −4 M) potentiated vascular tension in a concentration‐dependent manner ( P < 0.0001). Pretreatment with LNMA significantly suppressed the vasospastic effect of H 2 O 2 ( P < 0.0001). Pretreatment with either catalase or mannitol significantly reduced the vasospastic effect of H 2 O 2 ( P < 0.005, P < 0.002, respectively). Melatonin also significantly reduced the vasospastic effect of H 2 O 2 in a concentration‐dependent manner (H 2 O 2 10 −6 M, P < 0.0001: H 2 O 2 10 −5 M, P <0.0001: H 2 O 2 10 −4 M, P < 0.00001). Pretreatment with H 2 O 2 significantly inhibited the relaxation induced by the calcium ionophore A23187 ( P < 0.005). Treatment with melatonin prior to exposure to H 2 O 2 significantly restored the relaxation induced by A23187 ( P < 0.005). Results suggest that H 2 O 2 potentiates vascular tension in the human umbilical artery, perhaps by suppressing the endothelial synthesis of nitric oxide. Melatonin significantly suppressed the vasospastic effect of H 2 O 2 , possibly due to its ability to scavenge the hydroxyl radical.