The relationship between creatine kinase kinetics and exercise intensity in human forearm is unchanged by age
The relationship between creatine kinase kinetics and exercise intensity in human forearm is unchanged by age
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DOI：
10.1152/ajpendo.2000.279.2.e333
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发表时间：
2000-08-01
影响因子：
5.1
通讯作者：
Spencer, RGS
中科院分区：
文献类型：
--
作者：
Horská, A;Fishbein, KW;Spencer, RGS
使用P-31磁共振波谱法，评估健康年轻（n = 11，年龄34.7 +/- 5岁）和老年（n = 20，年龄73.5 +/- 8岁）受试者在静息、20%最大随意收缩（MVC）和40% MVC下间歇运动时前臂趾深屈肌的肌酸激酶（CK）反应动力学。运动导致无机磷酸盐（P-i）与磷酸肌酸（PCr）的平均比值显著增加，从静息值0.073 +/- 0.031（年轻）和0.082 +/- 0.037（老年）增加到0.268 +/- 0.140在40%MVC时，0.452 +/- 0.387（年轻，P < 0.01）和0.452 +/- 0.387（老年，P < 0.01）。在40%MVC时，细胞内pH值显著降低，从静息值7.08 +/- 0.08（年轻人）和7.08 +/- 0.11（老年人）降至6.84 +/- 0.19（年轻人，P < 0.05）和6.75 +/- 0.25（老年人，P < 0.05）。年轻组静息时的伪一级反应速率k（（PCr-->ATP））平均值为0.07 +/- 0.04 s（-1），老年组为0.07 +/- 0.03 s（-1）。在两个运动水平下，反应速率常数与静息值相比均增加，但只有静息值与20%MVC值之间的差异达到统计学显著性（P < 0.05），这表明两组的反应速率常数均高出86%。在两种运动水平下，年轻组和老年组之间的反应速率常数没有差异。与k（（PCr-->ATP））一样，在20%MVC时，运动期间通过CK反应的平均磷通量增加（老年组P 0.05），但在40%MVC时，两组均向静息值下降。我们研究中的数据表明，正常衰老不会显著影响与CK反应相关的代谢过程。
Using P-31 magnetic resonance spectroscopy, creatine kinase (CK) reaction kinetics was assessed in the forearm flexor digitorum profundus muscle of healthy young (n = 11, age 34.7 +/- 5 yr) and older (n = 20, age 73.5 +/- 8 yr) subjects at rest, intermittent exercise at 20% maximum voluntary contraction (MVC), and 40% MVC. Exercise resulted in a significant increase in the average ratio of inorganic phosphate (P-i) to phosphocreatine (PCr) from resting values of 0.073 +/- 0.031 (young) and 0.082 +/- 0.037 (older) to 0.268 +/- 0.140 (young, P < 0.01) and 0.452 +/- 0.387 (older, P < 0.01) at 40% MVC. At 40% MVC, intracellular pH decreased significantly, from resting values of 7.08 +/- 0.08 (young) and 7.08 +/- 0.11 (older) to 6.84 +/- 0.19 (young, P < 0.05) and to 6.75 +/- 0.25 (older, P < 0.05). Average values of the pseudo-first-order reaction rate k((PCr-->ATP)) at rest were 0.07 +/- 0.04 s(-1) in the young and 0.07 +/- 0.03 s(-1) in the older group. At both exercise levels, the reaction rate constant increased compared with the resting value, but only the difference between the resting value and the 20% MVC value, which showed an 86% higher reaction rate constant in both groups, reached statistical significance (P < 0.05). No difference in the reaction rate constant between the young and older groups was observed at either exercise level. As with k((PCr-->ATP)), the average phosphorus flux through the CK reaction increased during exercise at 20% MVC (P, 0.05 in the older group) but decreased toward resting values at 40% MVC in both groups. The data in our study suggest that normal aging does not significantly affect the metabolic processes associated with the CK reaction.