Wehmeyer N, Gunderson H, Nauman J, Savage S, Hartzell C
Department of Chemistry, Northern Arizona University, Flagstaff 86011.
Metabolism. 1994 Jan;43(1):38-43. doi: 10.1016/0026-0495(94)90155-4.
The level of hepatic glycogen synthesized directly from glucose was measured in rats with [1-13C]glucose. The nuclear magnetic resonance (NMR) spectrum of glucose was used to measure the distribution of the 13C label from C1 to the other carbons. Female Sprague-Dawley rats were surgically implanted with catheters in the left carotid artery and the right jugular vein, followed by a 3-day recovery period and a 24-hour fast to deplete liver glycogen. A 2-hour infusion of the fasted animal with [1-13C]glucose was immediately followed by the removal of blood and liver tissue. The liver was divided into the right, left, caudate, and medial lobes, and then freeze-clamped in liquid nitrogen and stored at -80 degrees C. The 13C NMR glucose spectra were obtained from glycogen that was isolated from each liver lobe and hydrolyzed to glucose with amyloglucosidase. Spectra were obtained at 50.3 MHz in a narrow-bore Gemini 200-MHz NMR spectrometer (Varian, Palo Alto, CA). The distribution of 13C onto glucose carbons was measured from these spectra, and the percent direct pathway was calculated to be 29% +/- 2.5%. Metabolic variation for the synthesis of glycogen within the liver was determined by measuring the direct pathway contribution in each of the four liver lobes. Percent direct pathway values were similar (P > .05) in right (35% +/- 4.9%), left (26% +/- 5.1%), medial (25% +/- 4.9%), and caudate (27% +/- 5.6%) lobes. For some of the animals, the direct pathway was determined by infusion with [6-13C]glucose.(ABSTRACT TRUNCATED AT 250 WORDS)
用[1-¹³C]葡萄糖测定了直接由葡萄糖合成的肝糖原水平。利用葡萄糖的核磁共振（NMR）谱来测量¹³C标记从C1到其他碳的分布情况。对雌性斯普拉格-道利大鼠进行手术，在其左颈动脉和右颈静脉植入导管，随后经过3天恢复期和24小时禁食以耗尽肝糖原。给禁食动物输注[1-¹³C]葡萄糖2小时后，立即采集血液和肝脏组织。将肝脏分为右叶、左叶、尾状叶和中叶，然后在液氮中进行冷冻钳夹，并储存在-80℃。从每个肝叶分离出糖原，用淀粉葡萄糖苷酶水解为葡萄糖，从而获得¹³C NMR葡萄糖谱。在一台窄孔Gemini 200-MHz NMR光谱仪（Varian公司，加利福尼亚州帕洛阿尔托）中于50.3 MHz下获得光谱。从这些光谱中测量¹³C在葡萄糖碳上的分布，并计算出直接途径的百分比为29%±2.5%。通过测量四个肝叶中直接途径的贡献来确定肝脏内糖原合成的代谢变化。右叶（35%±4.9%）、左叶（26%±5.1%）、中叶（25%±4.9%）和尾状叶（27%±5.6%）的直接途径百分比值相似（P＞0.05）。对于一些动物，通过输注[6-¹³C]葡萄糖来确定直接途径。（摘要截选至250字）
