Effects of starvation and refeeding on adult male rat diaphragm contractility, fatigue, and fiber types.
Effects of starvation and refeeding on adult male rat diaphragm contractility, fatigue, and fiber types.
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饥饿和再喂养对成年雄性大鼠膈肌收缩力、疲劳和纤维类型的影响。
DOI：
10.1152/jappl.1993.74.2.742
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发表时间：
1993
期刊：
影响因子：
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通讯作者：
Gentry,EI
中科院分区：
文献类型：
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作者：
Prezant,DJ;Valentine,DE;Kim,HH;Gentry,EI
研究了4.5天的急性饥饿对雄性大鼠膈肌收缩力、疲劳和纤维类型的影响，无论是单独的还是随后的重新喂食（随意）。在体外37℃直接刺激肋膈条制剂中测量收缩性和抗疲劳指标，与对照组相比，饥饿使体重减少28 +/- 1% (P < 0.001)，肋膈重量减少18 +/- 4% （P < 0.001）。抽搐和破伤风张力（按体重或横截面积归一化）不因饥饿而减少。饥饿在5hz刺激模式后疲劳抵抗指数显著增加，而在100 hz模式后则没有，这支持了疲劳抵抗取决于给定模式的能量需求的假设。饥饿大鼠膈肌中ⅰ型和ⅱ型纤维的比例与对照组相似，但ⅱ型纤维的横截面积显著减少了18 +/- 7% （P < 0.01）。因此，尽管饥饿后膈肌重量显著下降，但收缩性保持不变，抗疲劳能力增强（低输出模式）。这与II型纤维面积的减少是一致的。重新喂食恢复了所有参数，使身体或隔膜重量、收缩性、疲劳或纤维类型不再有显著差异。
The effects of 4.5 days of acute starvation, either alone or followed by refeeding (ad libitum), on diaphragm contractility, fatigue, and fiber types were studied in male rats. Contractility and fatigue resistance indexes were measured in an in vitro costal diaphragm strip preparation with direct stimulation at 37 degrees C. Compared with controls, starvation produced a 28 +/- 1% (P < 0.001) reduction in body weight and an 18 +/- 4% (P < 0.001) reduction in costal diaphragm weight. Twitch and tetanic tensions (normalized for weight or cross-sectional area) were not reduced by starvation. Starvation produced significant increases in fatigue resistance indexes after a 5-Hz stimulation paradigm but not after a 100-Hz paradigm, supporting the hypothesis that fatigue resistance is dependent on the energy demand of a given paradigm. The proportions of type I and type II fibers were similar between diaphragms of starved and control rats, but the cross-sectional area of type II fibers decreased significantly by 18 +/- 7% (P < 0.01). Thus, despite the significant decrease in diaphragm weight after starvation, contractility was preserved and fatigue resistance was increased (low-output paradigm). This is consistent with the decrease in type II fiber area. Refeeding restored all parameters so that there were no longer significant differences in body or diaphragm weight, contractility, fatigue, or fiber types.