Department of General Biology, Federal University of Viçosa, Viçosa, Minas Gerais, Brazil.
Int J Exp Pathol. 2011 Oct;92(5):299-307. doi: 10.1111/j.1365-2613.2011.00781.x. Epub 2011 Jul 8.
The aim of this study was to investigate the effects of Trypanosoma cruzi (T. cruzi) infection on myocardial morphology, single cardiomyocyte contractile function and exercise tolerance in rats. Adult Wistar rats were randomized into control (n = 14) and infected (n = 14) groups. Infected animals were inoculated with T. cruzi Y strain (300,000 trypomastigotes/50 g body weight). After 9 weeks, the animals were subjected to a treadmill running protocol. Then, the right atrium (RA) and left ventricle (LV) were removed for morphological and cell contractile evaluation. The infected animals exhibited a significant reduction in distance travelled, total time to fatigue and workload. In addition, these animals had hypertrophy, increased myocardial cellularity, and an increase in the proportion of collagen and blood vessels. RA and LV myocytes from infected animals showed marked contractile dysfunction under basal conditions and a reduced contractile response to β-adrenergic stimulation. The workload of infected animals was correlated closely with the amplitude of cell shortening of RA and LV myocytes. T. cruzi infection influenced the myocardial morphology and the mechanical properties of RA and LV single myocytes negatively and reduced exercise tolerance. Single cardiomyocyte contractile dysfunction could constitute an additional mechanism of cardiac impairment and reduced exercise tolerance in this infection.
本研究旨在探讨克氏锥虫（T. cruzi）感染对大鼠心肌形态、单个心肌细胞收缩功能和运动耐量的影响。成年 Wistar 大鼠随机分为对照组（n = 14）和感染组（n = 14）。感染组动物接种 T. cruzi Y 株（300,000 个锥虫/50 g 体重）。9 周后，动物进行跑步机运动方案。然后取出右心房（RA）和左心室（LV）进行形态和细胞收缩评估。感染动物的行进距离、总疲劳时间和工作量明显减少。此外，这些动物还表现出心肌肥大、心肌细胞增多、胶原和血管比例增加。感染动物的 RA 和 LV 心肌细胞在基础条件下表现出明显的收缩功能障碍，对β-肾上腺素刺激的收缩反应降低。感染动物的工作量与 RA 和 LV 心肌细胞缩短幅度密切相关。克氏锥虫感染对心肌形态和 RA 和 LV 单个心肌细胞的机械性能产生负面影响，并降低运动耐量。单个心肌细胞收缩功能障碍可能是该感染导致心脏损伤和运动耐量降低的另一个机制。
