关于静息和收缩状态下青蛙骨骼肌糖原分解调节的31P核磁共振研究。

31P nuclear magnetic resonance studies on the glycogenolysis regulation in resting and contracting frog skeletal muscle.

作者信息

Yamada T, Kikuchi K, Sugi H

机构信息

Department of Physiology, School of Medicine, Teikyo University, Tokyo, Japan.

出版信息

J Physiol. 1993 Jan;460:273-86. doi: 10.1113/jphysiol.1993.sp019471.

DOI:10.1113/jphysiol.1993.sp019471

PMID:8487196

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1175213/

Abstract

Regulation of glycogenolysis in frog skeletal muscle at rest and following contraction was studied by measuring the concentration of phosphate-containing metabolites and the intracellular pH (pHi) in CN-treated muscles, in which oxidative phosphorylation was inhibited by NaCN, using the 31P nuclear magnetic resonance (NMR) technique. 2. When CN-treated muscles were kept at rest, the phosphocreatine (PCr) concentration very slowly decreased with time with a corresponding increase of the inorganic phosphate (Pi) concentration, while the ATP concentration remained unchanged. The pHi changed in the alkaline direction for the first 3 h, and then started to change in the acidic direction. 3. When CN-treated muscles were tetanized for 10 s, the PCr concentration decreased with a corresponding increase of the Pi concentration and acidification of pHi, while the ATP concentration remained unchanged. 4. When CN-treated muscles were tetanized repeatedly (each for 2 s) at constant intervals, the pHi changed in the alkaline direction following the first and the second tetani, and then changed in the acidic direction following the subsequent tetani, indicating that the consumed ATP is first replenished by the Lohmann reaction, while glycogenolysis starts only when the total amount of contractile activity exceeds a critical value. 5. Irrespective of whether CN-treated muscles were kept at rest or tetanized repeatedly, the Pi concentration increased to about 8 mM (mmol/kg wet muscle) when glycogenolysis started, suggesting that the onset of glycogenolysis in CN-treated muscles is regulated by the Pi concentration. 6. The 'internal' buffering power of muscle cytosol was estimated to be 35 mM H+/pH unit in anaerobic muscles and 25 mM H+/pH unit in CN- and iodoacetic acid (IAA)-treated muscles. The 'internal' buffering power contains a contribution due to flux of carbon dioxide and lactic acid across the cell membrane. Evidence indicated that lactic acid flux is small.

摘要

利用³¹P核磁共振（NMR）技术，通过测量经氰化物（CN）处理的肌肉中含磷代谢物的浓度和细胞内pH值（pHi），研究了青蛙骨骼肌在静息状态和收缩后的糖原分解调节情况。在这些肌肉中，氧化磷酸化被NaCN抑制。2. 当经CN处理的肌肉处于静息状态时，磷酸肌酸（PCr）浓度随时间非常缓慢地下降，同时无机磷酸盐（Pi）浓度相应增加，而ATP浓度保持不变。在前3小时内，pHi向碱性方向变化，然后开始向酸性方向变化。3. 当经CN处理的肌肉进行10秒的强直收缩时，PCr浓度下降，Pi浓度相应增加，pHi酸化，而ATP浓度保持不变。4. 当经CN处理的肌肉以恒定间隔重复进行强直收缩（每次2秒）时，在第一次和第二次强直收缩后，pHi向碱性方向变化，随后的强直收缩后则向酸性方向变化，这表明消耗的ATP首先通过洛曼反应补充，而糖原分解仅在收缩活动总量超过临界值时才开始。5. 无论经CN处理的肌肉是处于静息状态还是重复进行强直收缩，当糖原分解开始时，Pi浓度都会增加到约8 mM（mmol/kg湿肌肉），这表明经CN处理的肌肉中糖原分解的开始受Pi浓度调节。6. 估计肌肉细胞质的“内部”缓冲能力在无氧肌肉中为35 mM H⁺/pH单位，在经CN和碘乙酸（IAA）处理的肌肉中为25 mM H⁺/pH单位。“内部”缓冲能力包含二氧化碳和乳酸跨细胞膜通量的贡献。有证据表明乳酸通量很小。