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高原鼢鼠和高原鼠兔骨骼肌糖酵解和肝脏乳酸代谢的差异

孙生祯, 魏莲, 魏登邦^*, 王多伟, 马本园

青海大学生物科学系，西宁 810016

摘要

高原鼠兔(Ochotona curzoniac)和高原鼢鼠(Myospalax baileyi)是青藏高原地区特有的土著动物。本文旨在探讨高原鼠兔和高原鼢鼠骨骼肌糖酵解和肝脏乳酸代谢的不同生理机制。我们克隆出两种动物肝脏中的丙酮酸羧化酶(pytuvate carboxylase, PC)基因的部分序列；应用real-time PCR法测定两种动物肝脏和骨骼肌中PC、LDH-A和LDH-B mRNA的表达水平；使用苹果酸偶联法测定肝脏中PC酶活力，并测定两种动物骨骼肌和肝脏中乳酸含量、乳酸脱氢酶(lactate dehydrogenase, LDH)活力；用聚丙烯酰胺凝胶电泳观察肝脏和骨骼肌LDH同工酶谱。结果显示：(1)高原鼢鼠骨骼肌LDH-B mRNA的表达量极显著高于高原鼠兔(P < 0.01)，而LDH-A mRNA的表达量没有差异(P > 0.05)；(2)高原鼠兔肝脏中PC、LDH-A和LDH-B mRNA的表达量都极显著高于高原鼢鼠(P < 0.01)；(3)高原鼠兔肝脏和骨骼肌中LDH和乳酸含量以及肝脏中PC活力均极显著高于高原鼢鼠(P < 0.01)；(4) LDH同工酶谱显示，高原鼠兔骨骼肌以LDH-A4、LDH-A3B、LDH-A2B2为主，而高原鼢鼠骨骼肌以LDH-AB3、LDH-B4为主；在高原鼠兔肝脏中LDH以LDH-A3B, LDH-A2B2, LDH-AB3 和 LDH-B4为主，而高原鼢鼠肝脏只有LDH-A4。以上结果表明，高原鼠兔通过提高骨骼肌无氧糖酵解的水平为其快速奔跑提供能量，通过提高肝脏中糖异生水平快速将骨骼肌运动所产生的乳酸转化为葡萄糖和糖原，所以减少了在低氧环境中对氧的依赖，而高原鼢鼠尽管生活在低氧的地下洞道，它通过提高骨骼肌有氧糖酵解的水平，为其持续的挖掘活动提供能量。

关键词： 高原鼠兔; 高原鼢鼠; 乳酸代谢; 丙酮酸羧化酶; 乳酸脱氢酶

分类号：S825

Differences of glycolysis in skeletal muscle and lactate metabolism in liver between plateau zokor (Myospalax baileyi) and plateau pika (Ochotona curzoniae)

SUN Sheng-Zhen, WEI Lian, WEI Deng-Bang^*, WANG Duo-Wei, MA Ben-Yuan

Department of Biology, Qinghai University, Xining 810016,China

Abstract

The plateau pika (Ochotona curzoniae) and plateau zokor (Myospalax baileyi) are specialized native species of the Qinghai-Tibetan plateau. The goal of this study was to examine physiological differences in skeletal muscle glycolysis and hepatic lactate metabolism between these two species. The partial sequence of pyruvate carboxylase (PC) gene was cloned and sequenced. The mRNA expression levels of PC and lactate dehydrogenases (LDH-A, LDH-B) were determined by real-time PCR. The enzymatic activity of PC was measured using malic acid coupling method. The concentration of lactic acid (LD) and the specific activities of LDH in liver and skeletal muscle of two species were measured. The different isoenzymes of LDH were determined by native polyacrylamide gel electrophoresis (PAGE). The results showed that, (1) LDH-B mRNA level in skeletal muscle of plateau zokor was significantly higher than that of plateau pika (P < 0.01), but no differences was found at LDH-A mRNA levels between them (P > 0.05); (2) PC, LDH-A and LDH-B mRNA levels in liver of plateau pika were significantly higher than those of plateau zokor (P < 0.01); (3) The LDH activity and concentration of LD in skeletal muscle and liver, as well as the PC activity in liver of plateau pika were significantly higher than those of plateau zokor (P < 0.01); (4) The isoenzymatic spectrum of lactate dehydrogenase showed that the main LDH isoenzymes were LDH-A₄, LDH-A₃B and LDH-A₂B₂ in skeletal muscle of plateau pika, while the main LDH isoenzymes were LDH-AB₃ and LDH-B₄ in skeletal muscle of plateau zokor; the main isoenzymes were LDH-A₃B, LDH-A₂B₂, LDH-AB₃ and LDH-B₄ in liver of plateau pika, while LDH-A₄ was the only isoenzyme in liver of plateau zokor. These results indicate that the plateau pika gets most of its energy for sprint running through enhancing anaerobic glycolysis, producing more lactate in their skeletal muscle, and converting lactate into glucose and glycogen in the liver by enhancing gluconeogenesis. As a result, the plateau pika has a reduced dependence on oxygen in its hypoxic environment. In contrast, plateau zokor derives most of its energy used for digging activity by enhancing aerobic oxidation in their skeletal muscle, although they inhabit hypoxic underground burrows.

Key words: plateau pika (Ochotona curzoniae); plateau zokor (Myospalax baileyi); lactate metabolism; pyruvate carboxylase; lactate dehydrogenase

收稿日期：2012-10-22　　录用日期：2012-12-31

通讯作者：魏登邦　　E-mail: weidengbang@163.com

引用本文：

孙生祯, 魏莲, 魏登邦, 王多伟, 马本园. 高原鼢鼠和高原鼠兔骨骼肌糖酵解和肝脏乳酸代谢的差异[J]. 生理学报 2013; 65 (3): 276-284.

SUN Sheng-Zhen, WEI Lian, WEI Deng-Bang, WANG Duo-Wei, MA Ben-Yuan. Differences of glycolysis in skeletal muscle and lactate metabolism in liver between plateau zokor (Myospalax baileyi) and plateau pika (Ochotona curzoniae). Acta Physiol Sin 2013; 65 (3): 276-284 (in Chinese with English abstract).