分娩应激期间血清离子镁的母婴转运：一项人体研究。

Maternal-fetal transfer of ionized serum magnesium during the stress of labor and delivery: a human study.

作者信息

Handwerker S M, Altura B T, Jones K Y, Altura B M

机构信息

Division of Maternal Fetal Medicine, NY Hospital Medical Center of Queens Flushing, USA.

出版信息

J Am Coll Nutr. 1995 Aug;14(4):376-81. doi: 10.1080/07315724.1995.10718524.

DOI:10.1080/07315724.1995.10718524

PMID:8568115

Abstract

OBJECTIVE

The purpose of this study was to compare levels and fractions of ionized magnesium in maternal venous serum with those in umbilical venous and arterial serum and to determine whether the maternal levels and fractions change during the stress of labor.

METHODS

Utilizing an ion-selective electrode, we determined levels and fractions of ionized magnesium (IMg2+) and levels of ionized calcium (ICa2+) in the maternal venous serum (MVS) of 12 parturients on admission and at the end of labor, as well as in the umbilical venous (UVS) and umbilical arterial serum (UAS) at delivery. A paired-sample study design was used.

RESULTS

Whereas mean levels of ICa2+ did not change significantly (p > 0.05) during labor, the mean (+/- SE) MVS levels of IMg2+ and total magnesium (TMg) fell from 0.50 +/- 0.01 and 0.80 +/- 0.02 mmol/L, respectively, on admission to 0.46 +/- 0.01 and 0.68 +/- 0.01 mmol/L (p < 0.01 and p < 0.001, respectively) at delivery. The ionized fraction, expressed as a percent (IMg2+/TMg x 100), increased from 62.8 +/- 2.1% to 67.8 +/- 1.2% (p < 0.05). In the UVS, the mean IMg2+ level (0.52 +/- 0.02 mmol/L) and the mean ionized fraction (73.6 +/- 1.7%) were higher than in MVS on admission or at delivery (p < 0.05 for all comparisons). The mean IMg2+ level in UAS (0.50 +/- 0.02 mmol/L) was lower than in UVS (p < 0.05), but higher than in MVS at delivery (p < 0.01). Finally, there were significant positive correlations between levels of magnesium (Mg) in MVS and in the UAS or UVS.

CONCLUSIONS

The observation that UAS levels of IMg2+ and TMg were similar to the MVS levels on admission despite the fall in maternal levels during labor points to the presence of homeostatic mechanisms in the fetus and placenta. It is possible that the presence of a higher fraction of unbound, free magnesium in UVS enhances magnesium transport to the fetus and thus homeostasis. Finally, we hypothesize that the fall in the levels of the biologically active form of Mg during labor may be yet another manifestation of the known stress responses to labor.

摘要

目的

本研究旨在比较母体静脉血清中离子化镁的水平和组分与脐静脉和脐动脉血清中的情况，并确定在分娩应激期间母体的水平和组分是否发生变化。

方法

我们使用离子选择性电极，测定了12名产妇入院时和分娩结束时母体静脉血清（MVS）中离子化镁（IMg2+）的水平和组分以及离子化钙（ICa2+）的水平，同时还测定了分娩时脐静脉血清（UVS）和脐动脉血清（UAS）中的这些指标。采用配对样本研究设计。

结果

分娩期间ICa2+的平均水平没有显著变化（p>0.05），而IMg2+和总镁（TMg）的平均（±SE）MVS水平分别从入院时的0.50±0.01和0.80±0.02 mmol/L降至分娩时的0.46±0.01和0.68±0.01 mmol/L（分别为p<0.01和p<0.001）。以百分比表示的离子化组分（IMg2+/TMg×100）从62.8±2.1%增加到67.8±1.2%（p<0.05）。在UVS中，平均IMg2+水平（0.52±0.02 mmol/L）和平均离子化组分（73.6±1.7%）在入院时或分娩时均高于MVS（所有比较p<0.05）。UAS中的平均IMg2+水平（0.50±0.02 mmol/L）低于UVS（p<0.05），但高于分娩时的MVS（p<0.01）。最后，MVS与UAS或UVS中的镁（Mg）水平之间存在显著正相关。