Postnatal changes in water content and proton magnetic resonance relaxation times in newborn rabbit tissues
Postnatal changes in water content and proton magnetic resonance relaxation times in newborn rabbit tissues
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DOI：
10.1203/00006450-199606000-00026
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发表时间：
1996-06-01
影响因子：
3.6
通讯作者：
Sulyok, E
中科院分区：
文献类型：
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作者：
Berenyi, E;Szendro, ZS;Sulyok, E
本研究采用质子核磁共振弛豫（H-1 NMR）测量方法，对新西兰大白兔幼崽皮肤、骨骼肌和肝脏组织中具有不同流动性的水组分进行了定量分析。在出生后0-1岁、24岁、48岁和72小时，对与母亲一起喂养并自由哺乳的幼犬（第一组）和与母亲分离并完全不哺乳的幼犬（第二组）进行了一系列研究。测定组织含水量（干燥法）和T-1、T-2弛豫时间（H-1 NMR法）。免费的。通过对T-2松弛曲线进行多分量拟合，计算松散结合层和紧密结合层的水分数。结果表明，皮肤含水量和T-1、T-2松弛时间均随年龄的增长而降低（p < 0.01），其中T-2的降低在II组明显高于I组（p < 0.05）。肌、肝水、T-1、T-2松弛时间不随年龄变化。肌肉水分保持不变，肝脏水分增加（p < 0.05）， T-1松弛时间在两组织中均无一致性变化，而T-2松弛时间显著减少（肌肉，p < 0.01）或有减少的趋势（肝脏，p < 0.06）。通过双指数分析，可以区分出T-2松弛曲线的快、慢分量，分别占皮肤、骨骼肌和肝脏总组织水的42-47%、50-57%和34-40%，与年龄和液体摄入量无关。T-2松弛曲线的三指数拟合使得组织水进一步划分为紧密结合（快组分）、松散结合（中组分）和自由（慢组分）的水组分成为可能。在所研究的所有组织中，松散结合部分占主导地位（皮肤，48-64%；肌肉，54-65%；肝脏，45-63%），其次是游离（皮肤，26-45%；肌肉，23-32%；肝脏，20-25%）和紧密结合的水部分（皮肤，6-14%；肌肉，10-16%；肝脏，14-33%）。出生后年龄和液体摄入量对这种分布模式没有明显影响。由此可见，大多数新生儿组织水是运动受限的。游离的、松散结合的和紧密结合的水似乎是相互关联的，并依赖于年龄、液体摄入量、所研究的组织及其水合作用。
In the present study, using proton nuclear magnetic resonance relaxation (H-1 NMR) measurements, an attempt was made to quantitate water fractions with different mobility in the skin, skeletal muscle, and liver tissues obtained from New Zealand white rabbit pups. Serial studies were carried out at the postnatal age of 0-1, 24, 48, and 72 h in pups nursed with their mothers and suckling ad libitum (group I) and in those pups separated from their mothers and completely withheld from suckling (group II). Tissue water content (desiccation method) and T-1 and T-2 relaxation times (H-1 NMR method) were measured. Free. loosely bound, and tightly bound water fractions were calculated by applying multicomponent fits of the T-2 relaxation curves. It was demonstrated that skin water content and T-1 and T-2 relaxation times decreased with age (p < 0.01), the decrease in T-2 proved to be more pronounced in group II than in group I (p < 0.05). Muscle and liver water, and T-1 and T-2 relaxation times did not change with age in the suckling pups. In response to withholding fluid intake muscle water remained constant, liver water increased paradoxically (p < 0.05), T-1 relaxation time showed no consistent change in either tissues, whereas T-2 relaxation time decreased significantly (muscle, p < 0.01) or tended to decrease (liver, p < 0.06). Using biexponential analysis fast and slow components of T-2 relaxation curve could be distinguished that accounted for 42-47%, 50-57%, and 34-40% of total tissue water in the skin, skeletal muscle, and liver, respectively, regardless of age and fluid intake. Triexponential fits of the T-2 relaxation curve made possible the further partition of tissue water into tightly bound (fast component), loosely bound (middle component), and free (slow component) water fractions. In all tissues studied, loosely bound fraction predominated (skin, 48-64%; muscle, 54-65%; liver, 45-63%), followed by the free (skin, 26-45%; muscle, 23-32%; liver, 20-25%) and the tightly bound water fraction (skin, 6-14%; muscle, 10-16%; liver, 14-33%). Postnatal age and fluid intake had no apparent influence on this pattern of distribution. It is concluded that the majority of neonatal tissue water is motion-constrained. The free, the loosely bound, and the tightly bound water fractions appear to be interrelated and dependent on age, fluid intake, the tissues studied, and their hydration.