EFFECT OF NUTRITIONAL DEPRIVATION ON DIAPHRAGM CONTRACTILITY AND MUSCLE-FIBER SIZE
EFFECT OF NUTRITIONAL DEPRIVATION ON DIAPHRAGM CONTRACTILITY AND MUSCLE-FIBER SIZE
复制标题
DOI：
10.1152/jappl.1986.60.2.596
复制
发表时间：
1986-02-01
影响因子：
3.3
通讯作者：
BELMAN, MJ
中科院分区：
文献类型：
--
作者：
LEWIS, MI;SIECK, GC;BELMAN, MJ
在成年大鼠中研究了营养剥夺对膈肌收缩和疲劳特性的影响。食物获取被限制为正常每日摄入量的三分之一，直到营养剥夺（ND）动物的体重达到.apprx。 50% 的对照 (CTL)。在体外神经肌肉条制剂中研究了等长收缩特性。与 CTL 相比，ND 动物的膈肌抽搐 (Pt) 和强直 (Po) 张力均显着降低； 然而，ND 组的 Pt/Po 较高。两组之间的力-频率曲线（归一化为 Po）的形状大体相似，除了在 5 和 10 脉冲/秒刺激时，ND 动物的膈肌产生更大的相对张力。隔膜疲劳是由 20 或 100 脉冲/秒的重复刺激引起的。 ND 动物隔膜的耐力时间（定义为张力降至初始值的 50% 所需的时间）在 20 和 100 脉冲/秒下均延长。疲劳诱导后，ND 和 CTL 隔膜的力-频率曲线立即向右移动。然而，与 CTL 相比，ND 组的这种右移减弱。营养缺乏对膈肌内不同类型纤维的比例没有影响，但确实导致快肌纤维和慢肌纤维的横截面积显着减少。对于快肌纤维，横截面积的减少明显更大。我们的结论是，膈肌收缩和疲劳特性的这些变化是由于营养不良对肌纤维横截面积的影响而发生的。
The influence of nutritional deprivation on the contractile and fatigue properties of the diaphragm was studied in adult rats. Food access was restricted to one-third of normal daily intake until the body weight of nutritionally deprived (ND) animals was .apprx. 50% of controls (CTL). Isometric contractile properties were studied in an in vitro nerve muscle strip preparation. Both twitch (Pt) and tetanic (Po) tensions of diaphragms from the ND animals were markedly reduced compared with CTL; however, Pt/Po was higher for the ND group. The shape of the force-frequency curve (normalized to Po) was generally similar between the two groups, except at 5 and 10 pulses/s stimulation, where greater relative tensions were produced in diaphragms from the ND animals. Diaphragm fatigue was induced by repetitive stimulation at either 20 or 100 pulses/s. Endurance time (defined as the time required for tension to fall to 50% of initial) of diaphragms from ND animals was prolonged at both 20 and 100 pulses/s. Immediately after induction of fatigue, force-frequency curves for both ND and CTL diaphragms were shifted to the right. However, this rightward shift was attenuated in the ND group compared with CTL. Nutritional deprivation had no effect on the proportions of different fiber types within the diaphragm but did result in a significant decrease in the cross-sectional area of both fast- and slow-twitch fibers. This decrease in cross-sectional area was significantly greater for fast-twitch fibers. We conclude that these changes in diaphragm contractile and fatigue properties occur as a result of the influence of malnutrition on muscle fiber cross-sectional area.