Federal University of São Paulo, São Paulo, Brazil.
Laboratory of Biophotonic, Nove de Julho University, São Paulo, Brazil.
J Gerontol A Biol Sci Med Sci. 2018 Mar 14;73(4):468-474. doi: 10.1093/gerona/glx244.
Exercise training effects on the contractility of aged myocardium have been investigated for more than 20 years, but the data are still unclear. This study evaluated the hypothesis that a swimming training (ST) may improve myocardial inotropism in older rats. Male Wistar rats aged 4 (young)-and 21 (old)-months-old were divided into young untrained (YNT), old untrained (ONT), and old trained (OTR; 6 weeks of ST) groups. Echocardiography and hemodynamic were employed to assess left ventricular morphology and function. Myocardial mechanics was evaluated on papillary muscles. Histological and immunoblotting were carried out to evaluate fibrosis and proteins that modulate the myocardial function and calcium handling. We found that older rats did not show cardiac dysfunction, but ONT group showed lower physical performance during a swimming test (YNT: 5 ± 2; ONT: -16 ± 0.4; OTR: 51 ± 3; Δ%, sec). Moreover, ONT group showed worse myocardial inotropism, in which it was reversed by ST (Peak developed tension: YNT: 6.2 ± 0.7; ONT: 3.9 ± 0.3; OTR: 6.9 ± 0.9; g/mm2). The ST was associated with preserved collagen content (YNT: 0.38 ± 0.05; ONT: 0.78 ± 0.12; OTR: 0.34 ± 0.09; %). Exercise partially mitigated the effects of aging on intracellular Ca2+-regulating protein (eg, L-Ca2+ channel and phospholamban) and β-isoform of myosin. Thus, we propose that these molecular alterations together with inhibition of collagen increase contribute to improved myocardial performance in older rats.
针对衰老心肌收缩力的运动训练效应已经研究了 20 多年，但数据仍不明确。本研究旨在验证游泳训练（ST）是否可改善老年大鼠的心肌变力性。将 4 月龄（青年）和 21 月龄（老年）雄性 Wistar 大鼠分为青年未训练组（YNT）、老年未训练组（ONT）和老年训练组（OTR；6 周 ST）。采用超声心动图和血流动力学评估左心室形态和功能。利用乳头肌评估心肌力学。进行组织学和免疫印迹分析，以评估纤维化和调节心肌功能及钙处理的蛋白。结果发现，老年大鼠未出现心功能障碍，但 ONT 组在游泳测试中的体能表现更差（YNT：5 ± 2；ONT：-16 ± 0.4；OTR：51 ± 3；%，秒）。此外，ONT 组的心肌变力性更差，而 ST 可逆转这一现象（最大张力：YNT：6.2 ± 0.7；ONT：3.9 ± 0.3；OTR：6.9 ± 0.9；g/mm2）。ST 与胶原含量的保持有关（YNT：0.38 ± 0.05；ONT：0.78 ± 0.12；OTR：0.34 ± 0.09；%）。运动部分缓解了细胞内 Ca2+调节蛋白（如 L-Ca2+通道和磷蛋白）和肌球蛋白β 同工型的衰老效应。因此，我们认为这些分子改变以及胶原抑制增加有助于改善老年大鼠的心肌功能。
