Myocardial Injury in Rats Exposed to High-Intensity Exercise Evaluated by 2-D Speckle Tracking Imaging
Zi-Ling You1, Zhi-Lin Ding1, Qin-Yun Ruan1
1Department of Ultrasound, First Affiliated Hospital of Fujian Medical University, Fuzhou, Fujian, China; Department of Ultrasound, National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, Fujian Medical University, Fuzhou, Fujian, China.
Ultrasound in Medicine & Biology
|September 9, 2023
Summary
High-intensity exercise may cause myocardial injury in rats, indicated by reduced strain and cellular changes. Two-dimensional speckle tracking imaging offers early detection of exercise-induced cardiac dysfunction.
Area of Science:
- Cardiovascular Physiology
- Exercise Science
- Diagnostic Imaging
Background:
- Understanding the cardiac effects of exercise intensity is crucial for preventing exercise-induced injuries.
- Left ventricular (LV) function and morphology are key indicators of cardiac health.
- Non-invasive imaging techniques are valuable for assessing cardiac changes.
Purpose of the Study:
- To evaluate left ventricular strain and morphological changes in Sprague Dawley rats subjected to varying exercise intensities.
- To investigate the impact of different exercise durations on cardiac structure and function.
- To assess the utility of 2-D speckle tracking imaging (STI) in detecting exercise-induced myocardial alterations.
Main Methods:
- Seventy-two rats were divided into sedentary, low, medium, and high-intensity running groups, with subgroups for 1, 4, and 8 weeks of exercise.
- Echocardiography was used to measure LV structure and left ventricular ejection fraction (LVEF).
- 2-D speckle tracking imaging (STI) assessed global longitudinal, circumferential, and radial strains (GLS, GCS, GRS). Histopathology examined myocardial cell size and collagen content.
Main Results:
- LV structure and LVEF remained unchanged across exercise groups and durations.
- High-intensity running (HIR) for 8 weeks significantly reduced GLS compared to sedentary and medium-intensity running groups.
- HIR also led to increased myocardial cell cross-sectional area (CSA), collagen volume fraction (CVF), and perivascular collagen area (PVCA), with observable cellular swelling and ill-defined boundaries.
Conclusions:
- Prolonged, high-intensity exercise can induce myocardial injury in rats.
- 2-D STI is a sensitive, non-invasive method for early detection of exercise-induced myocardial dysfunction, outperforming LVEF in this context.
