Biobehavioral and Health Sciences, University of Pennsylvania, School of Nursing, 135 Claire M. Fagin Hall, 418 Curie Boulevard, Philadelphia, PA 19104-4217, USA.
Eur J Appl Physiol. 2011 Nov;111(11):2735-41. doi: 10.1007/s00421-011-1909-0. Epub 2011 Mar 15.
Left ventricular performance is enhanced with chronic exercise training. Alterations in cardiomyocyte β-adrenergic responsiveness (BAR) may, in part, mediate this response. In this study, cardiac BAR and the expression of some key cardiac hypertrophic signaling molecules following 3 months of treadmill training were examined. Four-month old, female, Wistar Kyoto (WKY) rats were randomly assigned into either a sedentary (WKY-SED, n = 15) or an exercise-trained (WKY-TRD, n = 11) group. All rats were maintained on a 12-h light/dark cycle, and fed ad libitum. Exercise training consisted of motorized treadmill training at 25 m/min, 0% grade, 60 continuous minutes, 5 days/week for a period of 12 weeks. RT-PCR was used to establish basal cardiac calcineurin A, ANP, and AKT mRNA expression. In vitro cardiac BAR responsiveness was determined in Langendorff, isolated hearts. Following baseline, isoproterenol (ISO) was incrementally infused at concentrations ranging from 1 × 10(-10) to 1 × 10(-7) mol/L. There were no group differences for heart weight, heart to body weight ratio, calcineurin A, ANP, or AKT mRNA levels between WKY-SED and WKY-TRD. WKY-TRD showed enhanced cardiac BAR relative to WKY-SED (at ISO 1 × 10(-7) mol/L; P < 0.05). Moderate intensity treadmill exercise improved cardiac BAR responsiveness to a high concentration of isoproterenol. This adaptation was independent of training-induced alterations in cardiac hypertrophy or hypertrophic marker expression.
慢性运动训练可增强左心室功能。心肌细胞β-肾上腺素能反应性（BAR）的改变可能部分介导了这种反应。本研究观察了 3 个月跑步机训练后心脏 BAR 以及一些关键心脏肥厚信号分子的表达。将 4 月龄雌性 Wistar Kyoto（WKY）大鼠随机分为安静组（WKY-SED，n=15）或运动训练组（WKY-TRD，n=11）。所有大鼠均维持 12 小时光照/黑暗周期，并自由进食。运动训练包括以 25 m/min、0%坡度、60 分钟连续运动的方式，每周 5 天进行 12 周的电动跑步机训练。RT-PCR 用于建立基础心脏钙调神经磷酸酶 A、ANP 和 AKT mRNA 表达。在 Langendorff 离体心脏中，检测体外心脏 BAR 反应性。在基线后，以 1×10(-10)至 1×10(-7)mol/L 的浓度递增注入异丙肾上腺素（ISO）。WKY-SED 和 WKY-TRD 之间的心脏重量、心脏重量与体重比、钙调神经磷酸酶 A、ANP 或 AKT mRNA 水平没有组间差异。与 WKY-SED 相比，WKY-TRD 显示出增强的心脏 BAR（在 ISO 1×10(-7)mol/L 时；P<0.05）。中等强度的跑步机运动改善了心脏对高浓度异丙肾上腺素的 BAR 反应性。这种适应与训练引起的心脏肥大或肥大标志物表达的改变无关。
