Nandakumaran M, Dev B R, Makhseed M, Sugathan T N
Department of Obstetrics and Gynaecology, Faculty of Medicine, University of Kuwait, Kuwait.
Acta Paediatr Jpn. 1998 Aug;40(4):307-12. doi: 10.1111/j.1442-200x.1998.tb01937.x.
There have been no reports to date on glucose transport kinetics and the effect of graded hyperglycemia in the human placenta in non-steady-state conditions.
The transport kinetics of D-glucose in the human placenta was investigated in non-steady state conditions in vitro using perfusion of isolated placental lobules. National Cancer Tissue Culture (NCTC) 135 culture medium, diluted with Earle's buffered salt solution was used as the perfusate. 14C-Labeled D-glucose and water as reference were injected as a single bolus into the maternal arterial perfusate. Perfusate samples were collected and analyzed from the maternal and fetal venous outflows.
In four successful perfusions, differential transport rates of glucose in the maternal-fetal direction averaged 1.03, 1.02, 1.09, 1.04 and 1.03 times those of corresponding tritiated water transport rates for 10, 25, 50, 75 and 90% of efflux fractions, respectively. Glucose transport fraction, expressed as percentage of injected maternal dose averaged 84 +/- 3.1% of water transport fraction in the four perfusions. Glucose kinetic parameters expressed as area under the curve, elimination constant (Kel), clearance, time for maximum response, absorption rate and elimination rate averaged 0.25, 0.29, 3.96, 1.02, 0.25 and 0.18 times that of the corresponding tritiated water value, respectively. Neither the different kinetic parameters nor the transport fraction indices differed significantly when glucose concentrations in the same perfusions were raised successively from 5.56 to 27.80 and then to 55.6 mmol/L.
We speculate that within physiological limits, hyperglycemia per se plays no significant part in altering glucose transport kinetics across the human placenta in the maternal-fetal direction.
迄今为止，尚无关于非稳态条件下人胎盘葡萄糖转运动力学及分级高血糖影响的报道。
在体外非稳态条件下，通过灌注分离的胎盘小叶研究人胎盘D - 葡萄糖的转运动力学。用Earle氏缓冲盐溶液稀释的国家癌症组织培养基（NCTC）135作为灌注液。将14C标记的D - 葡萄糖和作为参照的水作为单次推注注入母体动脉灌注液中。从母体和胎儿静脉流出物中收集并分析灌注液样本。
在四次成功的灌注中，母体 - 胎儿方向葡萄糖的差异转运速率分别为相应的氚标记水转运速率的1.03、1.02、1.09、1.04和1.03倍，分别对应10%、25%、50%、75%和90%的流出分数。在四次灌注中，以注入母体剂量的百分比表示的葡萄糖转运分数平均为水转运分数的84±3.1%。以曲线下面积、消除常数（Kel）、清除率、最大反应时间、吸收率和消除率表示的葡萄糖动力学参数分别平均为相应氚标记水值的0.25、0.29、3.96、1.02、0.25和0.18倍。当同一灌注中葡萄糖浓度从5.56 mmol/L依次升高至27.80 mmol/L，然后再升至55.6 mmol/L时，不同的动力学参数和转运分数指数均无显著差异。
我们推测，在生理限度内，高血糖本身在改变人胎盘母体 - 胎儿方向的葡萄糖转运动力学方面不起重要作用。
