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高原鼠兔心脏中Ldh-c基因的表达及其对无氧糖酵解水平的影响

李筱, 魏莲, 汪洋, 许利娜, 魏琳娜, 魏登邦^*

青海大学医学院，西宁 810016

摘要

高原鼠兔(Ochotona curzoniae)对高原低氧环境有很强的适应性。本研究组前期研究显示，精子特异性乳酸脱氢酶(sperm-specific lactate dehydrogenase, LDH-C4)基因Ldh-c在高原鼠兔心、肝、脑、肌肉等组织中都有表达。本研究为了阐明LDH-C4对高原鼠兔心肌组织无氧糖酵解水平的影响，将20只高原鼠兔随机分为抑制剂组和空白对照组，每组10只。抑制剂组注射1 mL 1 mol/L LDH-C4特异性抑制剂N-isopropyl oxamate于高原鼠兔股二头肌，双侧各注射500 μL；空白对照组注射等量的生理盐水。应用荧光定量PCR和Western blot方法，测定LDH-C4基因Ldh-c在高原鼠兔心肌组织中的mRNA和蛋白表达水平；比较抑制剂组和空白对照组高原鼠兔心肌组织中乳酸脱氢酶(lactate dehydrogenase, LDH)活力；以及乳酸(lactate, LD)和ATP含量。结果显示，在mRNA和蛋白水平，Ldh-c基因在高原鼠兔心肌组织中均有表达，相对表达量分别为0.47 ± 0.06和0.68 ± 0.08；当肌肉注射1 mL 1 mol/L的N-isopropyl oxamate时，30 min后血液中抑制剂浓度为0.08 mmol/L，与空白对照组相比，抑制剂组心肌组织中LDH活力[(6.18 ± 0.48) U/mg vs (9.08 ± 0.58) U/mg]、LD [(0.21 ± 0.03) mmol/g vs (0.26 ± 0.04) mmol/g]和ATP含量[(4.40 ± 0.69) nmol/mg vs (6.18 ± 0.73) nmol/mg]显著下降(P < 0.01)。N-isopropyl oxamate对LDH活力、LD和ATP含量的抑制率分别为31.98%、20.90%和28.70%。以上结果说明：Ldh-c基因在高原鼠兔心肌组织中表达；LDH-C4通过催化无氧糖酵解过程，为心肌组织的活动提供至少28%的ATP，这可能降低高原鼠兔在低氧环境中对氧气的依赖，增强其对低氧环境的适应。

关键词： 高原鼠兔; 心肌组织; Ldh-c基因; N-isopropyl oxamate; 乳酸脱氢酶活力

分类号：Q95-3;Q955

[The expression of the sperm-specific lactate dehydrogenase gene Ldh-c in plateau pika (Ochotona curzoniae) cardiac muscle and its effect on the anaerobic glycolysis.] [Article in Chinese]

LI Xiao, WEI Lian, WANG Yang, XU Li-Na, WEI Lin-Na, WEI Deng-Bang^*

Medical School of Qinghai University, Xining 810016, China

Abstract

The plateau pika (Ochotona curzoniae) has a strong adaptability to hypoxic plateau environment. We found that the sperm-specific lactate dehydrogenase (LDH-C4) gene Ldh-c expressed in plateau pika cardiac muscle. In order to shed light on the effect of LDH-C4 on the anaerobic glycolysis in plateau pika cardiac muscle, 20 pikas were randomly divided into the inhibitor group and the control group, and the sample size of each group was 10. The pikas of inhibitor group were injected with 1 mL 1 mol/L N-isopropyl oxamate, a specific LDH-C4 inhibitor, in biceps femoris muscle of hind legs, each leg with 500 μL. The pikas of control group were injected with the same volume of normal saline (0.9% NaCl). The mRNA and protein expression levels of Ldh-c gene in plateau pika cardiac muscle were determined by real-time PCR and Western blot. The activities of LDH, and the contents of lactate (LD) and ATP in cardiac muscle were compared between the inhibitor group and the control group. The results showed that 1) the expression levels of Ldh-c mRNA and protein were 0.47 ± 0.06 and 0.68 ± 0.08, respectively; 2) 30 min after injection of 1 mL 1 mol/L N-isopropyl oxamate in biceps femoris muscle, the concentration of N-isopropyl oxamate in blood was 0.08 mmol/L; 3) in cardiac muscle of the inhibitor group and the control group, the LDH activities were (6.18 ± 0.48) U/mg and (9.08 ± 0.58) U/mg, the contents of LD were (0.21 ± 0.03) mmol/g and (0.26 ± 0.04) mmol/g, and the contents of ATP were (4.40 ± 0.69) nmol/mg and (6.18 ± 0.73) nmol/mg (P < 0.01); 5) the inhibition rates of N-isopropyl oxamate to LDH, LD and ATP were 31.98%, 20.90% and 28.70%, respectively. The results suggest that Ldh-c expresses in cardiac muscle of plateau pika, and the pika cardiac muscle may get at least 28% ATP for its activities by LDH-C4 catalyzed anaerobic glycolysis, which reduces the dependence on oxygen and enhances the adaptation to the hypoxic environments.

Key words: plateau pika (Ochotona curzoniae); cardiac muscle tissue; Ldh-c gene; N-isopropyl oxamate; LDH enzymatic activity

收稿日期：2014-12-30　　录用日期：2015-04-09

通讯作者：魏登邦　　E-mail: weidengbang@163.com

引用本文：

李筱, 魏莲, 汪洋, 许利娜, 魏琳娜, 魏登邦. 高原鼠兔心脏中Ldh-c基因的表达及其对无氧糖酵解水平的影响[J]. 生理学报 2015; 67 (3): 312-318.

LI Xiao, WEI Lian, WANG Yang, XU Li-Na, WEI Lin-Na, WEI Deng-Bang. [The expression of the sperm-specific lactate dehydrogenase gene Ldh-c in plateau pika (Ochotona curzoniae) cardiac muscle and its effect on the anaerobic glycolysis.] [Article in Chinese]. Acta Physiol Sin 2015; 67 (3): 312-318 (in Chinese with English abstract).