The role of calcium in the stimulation of gluconeogenesis by catecholamines.
The role of calcium in the stimulation of gluconeogenesis by catecholamines.
复制标题
钙在儿茶酚胺刺激糖异生中的作用。
DOI：
10.1016/0003-9861(81)90377-5
复制
发表时间：
1981
影响因子：
3.9
通讯作者：
Lardy,HA
中科院分区：
文献类型：
--
作者：
Yip,BP;Lardy,HA
在从禁食的正常大鼠中分离并在没有白蛋白或明胶的情况下培养的肝细胞中，去甲肾上腺素仅在不添加钙的情况下刺激来自果糖或二羟基丙酮的糖异生，并且仅在存在添加的钙的情况下刺激来自山梨糖醇或甘油的糖异生。因此，在分别代谢果糖或山梨糖醇作为代表性氧化或还原底物的肝细胞中研究了钙、去甲肾上腺素或钙与去甲肾上腺素组合对中间代谢物浓度的影响。以果糖为底物，添加钙增加了乳酸、丙酮酸、甘油醛3-磷酸和β-羟基丁酸的浓度，但降低了磷酸烯醇丙酮酸、2-磷酸甘油酸、3-磷酸甘油酸、葡萄糖6-磷酸、苹果酸、柠檬酸和α-酮戊二酸的浓度。以山梨糖醇为底物，钙增加了丙酮酸、苹果酸、β-羟基丁酸和葡萄糖的浓度。对于任一底物，钙都会导致乳酸/丙酮酸比率降低和β-羟基丁酸/乙酰乙酸比率增加，表明刺激还原当量从细胞质转移到线粒体。以山梨糖醇为底物，并有钙存在，去甲肾上腺素促进电子从细胞质进一步转移到线粒体 NAD。当细胞在中等钙存在的情况下暴露于儿茶酚胺时，胞质钙浓度增加，刺激线粒体α-甘油磷酸脱氢酶，从而刺激细胞区室之间的电子转移。
In hepatocytes isolated from fasted normal rats and incubated without albumin or gelatin, norepinephrine stimulated gluconeogenesis from fructose or dihydroxyacetone only in the absence of added calcium and from sorbitol or glycerol only in the presence of added calcium. The effects of calcium, norepinephrine, or calcium in combination with norepinephrine on the concentration of intermediary metabolites were therefore studied in hepatocytes metabolizing fructose or sorbitol as the representative oxidized or reduced substrate, respectively. With fructose as the substrate, addition of calcium increased the concentrations of lactate, pyruvate, glyceraldehyde 3-phosphate, and β-hydroxybutyrate, but decreased the concentrations of phosphoenolpyruvate, 2-phosphoglycerate, 3-phosphoglycerate, glucose 6-phosphate, malate, citrate, and α-oxoglutarate. With sorbitol as the substrate, calcium increased the concentrations of pyruvate, malate, β-hydroxybutyrate, and glucose. With either substrate, calcium caused a decrease in the lactate/ pyruvate ratio and an increase in the β-hydroxybutyrate/acetoacetate ratio, indicating the stimulation of transfer of reducing equivalents from cytosol to mitochondria. With sorbitol as the substrate, and with calcium present, norepinephrine promoted further electron transfer from cytosolic to mitochondrial NAD. Enhanced cytosolic calcium concentrations, when cells are exposed to catecholamines in the presence of medium calcium, stimulate the mitochondrial α-glycerophosphate dehydrogenase and thus the transfer of electrons between cell compartments.