Assel B, Rossi K, Kalhan S
Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106.
Am J Physiol. 1993 Sep;265(3 Pt 1):E351-6. doi: 10.1152/ajpendo.1993.265.3.E351.
Glucose turnover and glucose oxidation were quantified in six normal pregnant women serially throughout pregnancy, using [U-13C]glucose tracer in combination with open-circuit indirect respiratory calorimetry. Five normal nonpregnant women were studied for comparison. With advancing gestation and increase in maternal body weight, there was a proportionate increase in the rate of appearance (Ra) of glucose so that Ra expressed per kilogram body weight did not change from the first to third trimester. The tracer measured rate of glucose oxidation expressed per kilogram body weight also did not change significantly throughout pregnancy. Oxygen consumption (VO2) in pregnant subjects did not differ from that in nonpregnant subjects. However, the respiratory exchange ratio (RER) increased significantly during pregnancy (0.88 +/- 0.53 3rd trimester and 0.76 +/- 0.50 nonpregnant, P < 0.01). The estimated contribution of carbohydrate to VO2 measured by respiratory calorimetry was greater than that measured by the tracer method. This discrepancy became wider as the respiratory quotient increased in late pregnancy. These data suggest that maternal glucose metabolism adjusts throughout pregnancy to meet the increased demands of the conceptus. The discrepancy between tracer method and respiratory calorimetry was probably due to the contribution of (fetal) lipogenesis and (maternal) gluconeogenesis to RER.
在整个孕期对6名正常孕妇连续进行葡萄糖周转率和葡萄糖氧化的定量研究，采用[U-13C]葡萄糖示踪剂结合开路间接呼吸量热法。选取5名正常非孕妇作为对照进行研究。随着孕周增加和孕妇体重上升，葡萄糖的出现率（Ra）相应增加，因此按每千克体重计算的Ra在孕早期到孕晚期并无变化。按每千克体重计算的示踪剂测量的葡萄糖氧化率在整个孕期也无显著变化。孕妇的耗氧量（VO2）与非孕妇并无差异。然而，孕期呼吸交换率（RER）显著升高（孕晚期为0.88±0.53，非孕期为0.76±0.50，P<0.01）。通过呼吸量热法测得的碳水化合物对VO2的估计贡献大于示踪剂法测得的贡献。随着孕晚期呼吸商增加，这种差异变得更大。这些数据表明，孕期母体葡萄糖代谢会进行调整以满足胎儿不断增加的需求。示踪剂法与呼吸量热法之间的差异可能是由于（胎儿）脂肪生成和（母体）糖异生对RER的贡献。
