Cicogna A C, Padovani C R, Nardi S C, Okoshi M P
Faculdade de Medicina, UNESP, São Paulo.
Arq Bras Cardiol. 1993 Apr;60(4):215-9.
To evaluate the effects of age on mechanical performance of rat myocardium.
Left ventricular papillary muscles were isolated from male Wistar rats at 1, 3, 6 and 12 months of age. Muscles were studied isometrically and isotonically, stimulated at 0.2 Hz, perfused with Krebs-Henseleit solution having an external calcium concentration of 2.52 mM, and maintained at 28 degrees C.
Peak isometric developed tension was significantly higher in 1 month than 3, 6 and 12 months. Peak rate of isometric tension rise decreased substantially between 1, 3 and 12 months. Time to peak isometric developed tension showed a significant increase of both 3 and 12 months of age. Time to half relaxation increased significantly from 3 to 6 and from 3 to 12 months. Maximum rate of tension decline decreased from 3 to 6 and from 3 to 12 months. No difference in resting tension was noted among any group. Isotonically, peak shortening and time to peak shortening increased from 1 to 3 months of age. Time to half re-lengthening increased from 3 to 6 and from 3 to 12 months of age. No difference in peak shortening velocity, peak relaxation velocity and relative change in muscle length was noted among any groups.
The maturation affects the mechanical performance of cardiac muscle.
评估年龄对大鼠心肌力学性能的影响。
从1、3、6和12月龄的雄性Wistar大鼠中分离出左心室乳头肌。对肌肉进行等长和等张研究，以0.2 Hz的频率刺激，用外部钙浓度为2.52 mM的克雷布斯 - 亨塞尔特溶液灌注，并维持在28摄氏度。
1月龄时的等长收缩峰值张力显著高于3、6和12月龄。在1、3和12月龄之间，等长张力上升的峰值速率大幅下降。达到等长收缩峰值张力的时间在3月龄和12月龄时均显著增加。从3月龄到6月龄以及从3月龄到12月龄，半松弛时间显著增加。张力下降的最大速率从3月龄到6月龄以及从3月龄到12月龄均下降。各组之间静息张力无差异。在等张情况下，峰值缩短和达到峰值缩短的时间从1月龄到3月龄增加。从3月龄到6月龄以及从3月龄到12月龄，半再延长时间增加。各组之间在峰值缩短速度、峰值松弛速度和肌肉长度的相对变化方面无差异。
成熟过程会影响心肌的力学性能。
