Age and gender differences in excitation-contraction coupling of the rat ventricle
Age and gender differences in excitation-contraction coupling of the rat ventricle
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DOI：
10.1111/j.1469-7793.1998.533bh.x
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发表时间：
1998-09-01
影响因子：
5.5
通讯作者：
Rouleau, JL
中科院分区：
文献类型：
--
作者：
Leblanc, N;Chartier, D;Rouleau, JL
1.本研究的目的是确定潜在的青春期后的性别特异性差异的乳头肌的收缩性，电生理特性和钙瞬变的新鲜分离的心室肌细胞从大鼠心脏。在等长和等张条件下（29 ℃）研究了2至14个月大雄性和雌性大鼠乳头肌的收缩。年轻（2-4个月）的雄性和雌性大鼠心脏表现出相似的收缩特征，而6个月及以上的雌性大鼠的乳头肌表现出较小的等长收缩和等张收缩，在起始和舒张阶段的最大张力和缩短发展速率和下降速率（+/- DT/dt和+/- DL/dt）较小，收缩时间短于年龄匹配的雄性大鼠.为了探索解释这些差异的可能的细胞基础，使用全细胞膜片钳技术（35 ° C）从新鲜分离的肌细胞记录动作电位和宏观电流。3个月和B个月大的大鼠的雄性和雌性肌细胞的动作电位没有随年龄或性别而变化。与这些结果一致，内向整流（I-K1），瞬时外向（I-to）和持续（I-K）K+电流的幅度（以pA pF（-1）表示），电压依赖性和动力学显示很少，如果有任何年龄或性别的依赖性。在来自3、6和9月龄的雄性和雌性大鼠的装载铯的肌细胞（35 ℃）中测量的L型Ca 2+电流（I-Ca（L））表现出相似的特征。相比之下，虽然用indo-1测量的Ca 2+瞬变在3个月大的雄性和雌性大鼠肌细胞之间是相似的，但与在相似年龄的雄性大鼠中记录的那些相比，10个月大的雌性肌细胞的Ca 2+瞬变显著降低并且显示出降低的松弛速率。这些结果表明，重要的性别相关的变化，兴奋收缩耦合发生青春期后，可能是由于钙处理能力的差异，在肌浆网的水平。
1. The objective of this study was to determine potential post-pubertal gender-specific differences in the contractility of papillary muscles, the electrophysiological properties and Ca2+ transients of freshly dissociated ventricular myocytes from the rat heart.2. The contractions of rat papillary muscles from 2- to 14-month-old male and female rats were studied under isometric and isotonic conditions (29 degrees C). While the hearts of young (2-4 months) male and female rats displayed a similar contractile profile, papillary muscles of female rats aged 6 months and older exhibited smaller isometric and isotonic contractions, smaller maximal rates of tension and shortening development and decline (+/- DT/dt and +/- DL/dt) velocities during both the onset and relaxation phases, and shorter contractions than age-matched males.3. To explore the possible cellular basis accounting for these differences,, action potentials and macroscopic currents were recorded from freshly dissociated myocytes using the whole-cell patch clamp technique (35 degrees C). Action potentials from male and female myocytes of 3- and B-month-old rats did not vary as a function of age or gender. Consistent with these results, the magnitude (expressed in pA pF(-1)), voltage-dependence and kinetics of the inward rectifier (I-K1), transient outward (I-to) and sustained (I-K) K+ currents displayed little, if any dependence on age or gender.4. L-type Ca2+ current (I-Ca(L)) measured in caesium-loaded myocytes (35 degrees C) from male and female rats of 3, 6 and 9 months of age exhibited similar characteristics. In contrast, while Ca2+ transients measured with indo-1 were similar between 3-month-old male and female rat myocytes, Ca2+ transients of 10-month-old female myocytes were significantly reduced and showed a diminished rate of relaxation in comparison with those recorded in male rats of similar age.5. These results suggest that important gender-related changes in excitation-contraction coupling occur following puberty, probably due to differences in Ca2+ handling capabilities at the level of the sarcoplasmic reticulum.