Groban Leanne, Jobe Harrison, Lin Marina, Houle Timothy, Kitzman Dalane A, Sonntag William
Department of Anesthesiology, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157-1009, USA.
J Gerontol A Biol Sci Med Sci. 2008 Sep;63(9):911-20. doi: 10.1093/gerona/63.9.911.
Whether the lusitropic potential of short-term exercise in aged rats is linked to an augmentation in the growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis and an alteration in the cardiac renin angiotensin system (RAS) is unknown. Old (28-month-old) male, Fischer 344xBrown Norway rats were randomized to 4 weeks of GH supplementation (300 microg subcutaneous, twice daily) or 4 weeks of treadmill running, or were used as sedentary controls. Six-month-old rats, sedentary or exercised, were used as young controls. Training improved exercise capacity in old animals. Exercise and GH attenuated age-related declines in myocardial relaxation despite an exercise-induced suppression of IGF-1. The regulatory protein, sarcoplasmic Ca2+ adenosine triphosphatase (SERCA2), increased with exercise but not GH. Among aged rats, the cardiac RAS was not altered by training or GH. Thus, the signaling pathway underlying the lusitropic benefit of short-term habitual exercise in the aged rat may be distinct from GH-mediated benefits and independent of the cardiac RAS.
短期运动对老年大鼠舒张功能的潜在影响是否与生长激素/胰岛素样生长因子-1（GH/IGF-1）轴的增强及心脏肾素血管紧张素系统（RAS）的改变有关尚不清楚。将28月龄的老年雄性Fischer 344xBrown Norway大鼠随机分为三组，分别接受为期4周的生长激素补充（皮下注射300微克，每日两次）、4周的跑步机跑步训练，或作为久坐对照组。6月龄的大鼠，无论久坐还是运动，均作为年轻对照组。训练提高了老年动物的运动能力。尽管运动导致IGF-1受到抑制，但运动和生长激素均减轻了与年龄相关的心肌舒张功能下降。调节蛋白肌浆网Ca2+ 三磷酸腺苷酶（SERCA2）随运动增加，但不随生长激素增加。在老年大鼠中，心脏RAS不受训练或生长激素的影响。因此，短期习惯性运动对老年大鼠舒张功能有益的信号通路可能不同于生长激素介导的益处，且独立于心脏RAS。
