Trang T T, Viires N, Aubier M
INSERM U 226, Faculté Bichat, Paris, France.
J Dev Physiol. 1992 Jan;17(1):1-6.
This study was designed to determine the developmental changes in the functional characteristics of the rat diaphragm. A total of 150 animals were studied at 1, 3, 5, 7 and 9 weeks of postnatal age. Body and diaphragm muscle weights were measured. Diaphragm strips were studied in an in vitro preparation to assess muscle contractile and endurance properties. Total diaphragm weight increased considerably, by a factor of 23 over the 9 week-period of study and was highly correlated with body weight (r = 0.93, P less than 0.01). However, the ratio of diaphragm-to-body weight decreased progressively with age. In comparison with those from older animals, diaphragms from 1 and 3 weeks old animals: (1) generated similar force normalized for muscle weight but a lower force normalized for fibre cross-sectional area (P less than 0.05), (2) had longer time-to-peak tension and one-half relaxation times (P less than 0.01) and (3) were more resistant to fatigue (P less than 0.01). The mechanisms underlying the diaphragm functional development were discussed.
本研究旨在确定大鼠膈肌功能特性的发育变化。总共对150只出生后1、3、5、7和9周龄的动物进行了研究。测量了体重和膈肌重量。在体外制备中研究膈肌条带，以评估肌肉收缩和耐力特性。在9周的研究期间，膈肌总重量显著增加，增加了23倍，并且与体重高度相关（r = 0.93，P < 0.01）。然而，膈肌与体重的比值随年龄逐渐降低。与老年动物的膈肌相比，1周龄和3周龄动物的膈肌：（1）以肌肉重量归一化后的产生力相似，但以纤维横截面积归一化后的产生力较低（P < 0.05），（2）达到峰值张力的时间和一半松弛时间更长（P < 0.01），（3）对疲劳更具抵抗力（P < 0.01）。讨论了膈肌功能发育的潜在机制。
