These experiments were designed to determine whether glycogenolysis was influenced by the glycogen concentration of vascular smooth muscle. Segments of hog carotid artery smooth muscle were allowed to synthesize variable amounts of 1-[13C]glucosyl units of glycogen. Artery segments were then isometrically contracted in the presence of 2-[13C]glucose. Prior to and after isometric contraction, measurements were made of tissue glycogen content and superfusate glucose and lactate concentrations. 2-[13C]Lactate and 3-[13C]lactate peak intensities in the superfusate were measured using 13C-NMR spectroscopy. The tissue glycogen content decreased exponentially during the 4.5 h of isometric contraction (R2 = 0.990), despite more than a 3-fold range of glycogen concentration prior to contraction. The extent of glycogen utilization during a 3 h isometric contraction varied linearly with the precontraction glycogen concentration (R2 = 0.727). Lactate production specifically from glycogen breakdown increased with an increase in precontraction glycogen concentration (R2 = 0.620). During a 3 h isometric contraction neither the glucose utilization (R2 = 0.007) nor lactate production specifically produced from glucose (R2 = 0.00002) varied with the precontraction glycogen concentration. It is concluded that the rate of glycogenolysis is determined by the content of glycogen during prolonged contractions. In addition, precontraction glycogen levels influence the pathway for glycogen utilization but not the pathway for glucose utilization. Therefore, glycolysis and glycogenolysis behave independently in vascular smooth muscle.

译文

这些实验旨在确定糖原分解是否受血管平滑肌糖原浓度的影响。允许猪颈动脉平滑肌段合成可变量的1-[13C] 糖原葡萄糖单元。然后在2-[13C] 葡萄糖存在下等距收缩动脉段。在等距收缩之前和之后,测量组织糖原含量和超融合物葡萄糖和乳酸浓度。使用13C-NMR光谱测量超融合物中的2-[13C] 乳酸和3-[13C] 乳酸峰强度。组织糖原含量在等距收缩的4.5小时内呈指数下降 (R2 = 0.990),尽管收缩前糖原浓度超过3倍。在3 h等距收缩期间糖原利用的程度随收缩前糖原浓度线性变化 (R2 = 0.727)。糖原分解产生的乳酸产量随着收缩前糖原浓度的增加而增加 (R2 = 0.620)。3小时的等距收缩葡萄糖利用率 (R2 = 0.007) 和特别由葡萄糖产生的乳酸产量 (R2 = 0.00002) 都不随收缩前糖原浓度而变化。结论是糖原分解速率由长期收缩期间糖原含量决定。此外,收缩前糖原水平会影响糖原利用的途径,但不会影响葡萄糖利用的途径。因此,糖酵解和糖原分解在血管平滑肌中独立运作。

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