不同周龄大鼠心肌细胞收缩/舒张功能的研究

The contraction and relaxation functions of cardiac myocytes in rats of different ages

目的研究不同周龄对大鼠心肌细胞收缩／舒张功能的影响。方法SD大鼠分为三个周龄组：A组（12～15周）、B组（36～41周）和C组（51～55周），并以常规酶解法分离成年大鼠心肌细胞，观察分离即刻（D时间点）、复钙1h后（E时间点）和电刺激10min后（F时间点）心肌细胞成活率，采用IonOptix单细胞动缘探测系统同步检测心肌细胞的收缩幅度、收缩／舒张速度和钙瞬变等，这些指标均由计算机自动实时采集并记录。结果复钙1h后和电刺激10min后心肌细胞成活率降低均有统计学意义（P〈0．05或P〈0．01），周龄越大越明显，随着周龄的增大，心肌细胞收缩幅度（峰值高度，ph）、心肌细胞收缩幅度／单个心肌细胞的长度百分比（ph／bl％）、最大收缩速率（maximal velocity of contraction，＋dL／dt）、最大舒张速率（maximal velocity of relaxation，-dL／dt）和钙瞬变幅度（⊿FFI）降低，ph在A组、B组和C组分别为（0．14±0．06），（0．12±0．05），（0．11±0．05）／zmph／b1％分别为（9．17±3．54）％、（7．14±2．58）％和（6．56±2．36）％；＋dL／dt分别为（2．01±0．74），（1．82±0．51），（1．51±0．56）μm／s；-dL／dt分别为（2．10±0．75），（1．70±0．62），（1．41±0．52）μm／s；⊿FFI分别为（0．38±0．05），（0．35±0．04），（0．25±0．05）。其中C组ph／bl%、＋dL／dt、-dL／dt和么FFI均较A组显著降低（P〈0．05），降低幅度分别为27％，26％，33％和31％。结论随着周龄的增大，分离大鼠心肌细胞的成活率下降，大鼠心肌细胞的收缩／舒张功能降低，钙瞬变幅度减小。

Objective To investigate the changes of contraction and relaxation functions of cardiac myocytes in rats of different ages and the possible mechanism involved. Methods SD rats were divided into three groups：group A（ 12-15weeks）, group B （36-41weeks）and group C （51-55weaks）. Cardiac myocytes were separated by enzyme and observed after separation,after loading calcium for 1 h and after electric stimulation for 10 min. The contraction amplitude was measured with video edge tracker method. The following indexes including contraction amplitude（ph）, contraction amplitude/single cardiac myocyte length percentage（ph/bl% ）, maximal velocity of contraction （±dL/dt）, maximal velocity of relaxation （±dL/dt）and calcium transients（dFFI） were analysed by the computer. Results With increasing age of the rats, the survival rates of myocytes declined after loading calcium for 1 h and electric stimulation for 10 min, with significant difference（P〈0.05 or P〈0.01）. ph Of groups A, B and C were （0.14±0.06）, （0.12±0.05） and （0. 11±0.05）μm respectively;ph/bl% of the three groups were （9.17±3.54）% ,（7.14±2.58）% and（6.56±2.36） % respectively; ±dL/dt of the three groups were （2.01±0.74）, （1.82±0. 51）and（1.51±0.56）μm/s respectively; - dL/dt of the three groups were （2. 1 ±0. 75 ）, （1. 70±0.62）and（1.41±0. 52）μm /s respectively; ⊿FFI of the three groups were （0.38±0.05）, （0.35±0.04）and（0.25±0.05） respectively, ph/bl%, ＋dL/dt,-dL/dt and ⊿FFI of group C were lower than those of group A with significant difference. These indexes were lower by 27%,26% ,33%and 31% respectively. Conclusion With increasing rat age, the survival rates of myocytes decrea ses, and contraction function, relaxation function and calcium transients of cardiac myocytes decline.