Rogers S, Gavin J R, Hammerman M R
Am J Physiol. 1985 Aug;249(2 Pt 2):F256-62. doi: 10.1152/ajprenal.1985.249.2.F256.
Gluconeogenesis is a major metabolic function of the renal proximal tubular cell. To characterize the regulation of this process in proximal tubule, glucose production from gluconeogenic precursors was measured in proximal tubular segments prepared from dog kidney. Production of glucose was a linear function of time for up to 120 min of incubation at 37 degrees C under a variety of conditions. Lowering the pH of incubation media from 7.5 to 7.0 increased glucose synthesis. Production of glucose was inhibited by 3-mercaptopicolinate. Incubation of proximal tubular segments with insulin diminished synthesis of glucose. Incubation of segments with tumor-promoting phorbol esters, 12-O-tetradecanoylphorbol-13-acetate or phorbol 12,13-dibutyrate, resulted in decreased production of glucose. This effect was not observed following incubation with the inactive phorbol ester 4 alpha-phorbol. Changes in glucose synthesis could not be attributed to alterations in cell viability or in rates of glucose oxidation induced by experimental maneuvers. Our findings confirm the usefulness of proximal tubular segments for characterization of metabolic processes in this portion of the nephron. The experimental results are consistent with a role for protein kinase C in the control of gluconeogenesis in proximal tubule.
糖异生是肾近端小管细胞的一项主要代谢功能。为了阐明近端小管中该过程的调节机制，我们在狗肾制备的近端小管节段中测量了糖异生前体生成葡萄糖的情况。在37℃下孵育长达120分钟的各种条件下，葡萄糖生成是时间的线性函数。将孵育培养基的pH从7.5降至7.0可增加葡萄糖合成。3-巯基吡啶甲酸盐可抑制葡萄糖生成。近端小管节段与胰岛素一起孵育可减少葡萄糖合成。近端小管节段与促肿瘤佛波酯、12-O-十四酰佛波醇-13-乙酸酯或佛波醇12,13-二丁酸酯一起孵育，会导致葡萄糖生成减少。与无活性佛波酯4α-佛波醇一起孵育后未观察到这种效应。葡萄糖合成的变化不能归因于实验操作引起的细胞活力改变或葡萄糖氧化速率改变。我们的研究结果证实了近端小管节段在表征肾单位这一部分代谢过程中的有用性。实验结果与蛋白激酶C在近端小管糖异生控制中的作用一致。
