豚鼠的经胎盘梯度

Transplacental gradients in the guinea pig.

作者信息

Woods L L, Thornburg K L, Faber J J

出版信息

Am J Physiol. 1978 Aug;235(2):H200-7. doi: 10.1152/ajpheart.1978.235.2.H200.

DOI:10.1152/ajpheart.1978.235.2.H200

Abstract

We measured plasma concentrations of Na+, K+, Mg2+, Cl-, Ca2+, HCO3-, phosphate, lactate, glucose, total amino acids, and total protein, and also the total (freezing point depression) osmolality and the colloid osmotic pressures. Conversion of chemically measured concentrations to osmolalities showed that unrecognized solute (s) were present in maternal (7 mM) and fetal (12 mM) plasma. Statistically reliable transplacental gradients existed only for calcium ion, phosphate, and amino acids, Ionic Na, K Mg, Cl, Ca, HCO3 and lactate were in electrochemical equilibrium at potential differences of -4.2 to +1.3 mV. Total plasma osmolalities were not significantly different in maternal and fetal plasmas in preparations in good condition, but fetal plasma osmolalities rose due to lactate secretion in asphyxiated fetuses. Colloid osmotic pressures were about 5 cmH2O higher in maternal plasmas before 45 days gestation and about 6 cmH2O higher in fetal plasmas after 60 days gestation. In the guinea pig, colloid osmotic pressures are at least as important as intravascular pressures in the regulation of transplacental water flow.

摘要

我们测量了血浆中Na⁺、K⁺、Mg²⁺、Cl⁻、Ca²⁺、HCO₃⁻、磷酸盐、乳酸盐、葡萄糖、总氨基酸和总蛋白的浓度，还测量了总（冰点降低）渗透压和胶体渗透压。将化学测量的浓度转换为渗透压后发现，母体（7 mM）和胎儿（12 mM）血浆中存在未被识别的溶质。仅钙离子、磷酸盐和氨基酸存在统计学上可靠的跨胎盘梯度，离子Na、K、Mg、Cl、Ca、HCO₃⁻和乳酸盐在-4.2至+1.3 mV的电位差下处于电化学平衡状态。在状况良好的制剂中，母体和胎儿血浆的总血浆渗透压无显著差异，但在窒息胎儿中，由于乳酸分泌，胎儿血浆渗透压升高。妊娠45天前母体血浆中的胶体渗透压约高5 cmH₂O，妊娠60天后胎儿血浆中的胶体渗透压约高6 cmH₂O。在豚鼠中，胶体渗透压在调节跨胎盘水流方面至少与血管内压力同样重要。