Coceani F, Kelsey L, Ackerley C, Rabinovitch M, Gelboin H
Research Institute, Hospital for Sick Children, Toronto, ON, Canada.
Can J Physiol Pharmacol. 1994 Mar;72(3):217-26. doi: 10.1139/y94-034.
Our previous investigations have implicated a cytochrome P450 mechanism in the oxygen contraction of the ductus arteriosus and, by extension, in the closure of the vessel at birth. This study was undertaken in fetal and newborn sheep to characterize the ductal cytochrome and gather insight into its operation. Other tissues, vascular and extravascular, were used as a reference. Benzo[a]pyrene hydroxylation (a marker for the 3-methylcholanthrene-inducible isozyme) and aminopyrine N-demethylation (a marker for the glucocorticoid-inducible isozyme) had insignificant activity in the ductus and aorta from fetal sheep, and no increase was noted after exposing the animal in utero to beta-naphthoflavone or dexamethasone, both alone and in combination with phenobarbital. However, dexamethasone and, particularly, dexamethasone plus phenobarbital produced a variable constriction of the fetal ductus. No monooxygenase activity was found in the naturally closing ductus of the newborn. Conversely, both enzyme reactions were measurable in the fetal liver, and they became more active after treatment with the inducers or at birth. Scanning immunoelectron microscopy of cultured endothelial and muscle cells from both ductus and aorta showed specific gold labelling for the glucocorticoid-inducible cytochrome P450 only in ductal muscle. By transmission electron microscopy, this immunoreactivity was located along the sarcolemma and in the sarcoplasmic reticulum. These findings indicate the presence in the ductus arteriosus of a cytochrome P450 belonging to the 3A subfamily. However, considering the uneven action of the inducers on enzyme activity in ductal tissue and muscle tone, the role of this cytochrome in closure of the vessel at birth remains to be ascertained.
我们之前的研究表明，细胞色素P450机制参与动脉导管的氧收缩过程，进而与出生时该血管的闭合有关。本研究以胎儿和新生绵羊为对象，旨在鉴定导管中的细胞色素，并深入了解其作用机制。其他组织，包括血管组织和血管外组织，用作对照。苯并[a]芘羟化作用（3-甲基胆蒽诱导同工酶的标志物）和氨基比林N-脱甲基作用（糖皮质激素诱导同工酶的标志物）在胎儿绵羊的动脉导管和主动脉中活性不显著，且在子宫内给动物单独或联合苯巴比妥使用β-萘黄酮或地塞米松后，活性未增加。然而，地塞米松，尤其是地塞米松加苯巴比妥可使胎儿动脉导管产生不同程度的收缩。在自然闭合的新生动脉导管中未发现单加氧酶活性。相反，在胎儿肝脏中可检测到这两种酶反应，且在用诱导剂处理后或出生时其活性增强。对动脉导管和主动脉培养的内皮细胞和肌肉细胞进行扫描免疫电子显微镜检查发现，仅在导管肌肉中存在糖皮质激素诱导的细胞色素P450特异性金标记。通过透射电子显微镜观察，这种免疫反应性位于肌膜和肌浆网。这些发现表明动脉导管中存在属于3A亚家族的细胞色素P450。然而，考虑到诱导剂对导管组织酶活性和肌张力的作用不均衡，该细胞色素在出生时血管闭合中的作用仍有待确定。
