Nagata N, Rasmussen H
Proc Natl Acad Sci U S A. 1970 Feb;65(2):368-74. doi: 10.1073/pnas.65.2.368.
Isolated segments of renal tubules prepared from rat kidney cortex were capable of sustained rates of gluconeogenesis when lactate served as substrate. An increase in external Ca(++), or the addition of parathyroid hormone at a fixed Ca(++) concentration led to enhanced rate of gluconeogenesis. However, parathyroid did not increase gluconeogenesis in the absence of external Ca(++) even though it caused a rise in 3'5' AMP whether Ca(++) was present or absent. Metabolite profiles showed that either an increase in external Ca(++), or the addition of hormone in the presence of calcium led to qualitatively very similar changes. However, the addition of hormone had little effect upon metabolite levels in the absence of extracellular calcium even though an increase in extracellular H(+) enhanced gluconeogenesis under similar conditions. These results are discussed in relationship to the close association of 3'5' AMP and Ca(++) in a variety of cellular systems.
从大鼠肾皮质制备的离体肾小管段,以乳酸为底物时能够维持糖异生速率。细胞外钙离子浓度增加,或在固定钙离子浓度下添加甲状旁腺激素,会导致糖异生速率加快。然而,即使无论有无钙离子存在甲状旁腺激素都会使3',5'-环磷酸腺苷(3',5' AMP)水平升高,但在没有细胞外钙离子的情况下,甲状旁腺激素并不会增加糖异生。代谢物谱显示,细胞外钙离子浓度增加,或在有钙存在时添加激素,会导致在性质上非常相似的变化。然而,在没有细胞外钙的情况下,添加激素对代谢物水平影响很小,尽管在类似条件下细胞外氢离子浓度增加会增强糖异生。结合3',5' AMP和钙离子在多种细胞系统中的紧密联系对这些结果进行了讨论。