Exercise training improves cardiac performance in diabetes: in vivo demonstration with quantitative cine-MRI analyses

Departments of 1 Physical Therapy and Rehabilitation Science and 2 Molecular and Integrative Physiology, and 3 Hoglund Brain Imaging Center, University of Kansas Medical Center, Kansas City; and 4 Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas Submitted 5 May 2006 ; accepted in final form 25 October 2006 Diabetic cardiomyopathy is a distinct myocardial complication of the catabolic state of untreated insulin-dependent diabetes mellitus in the streptozotocin-induced diabetic rat. Exercise training has long been utilized as an effective adjunct to pharmacotherapy in the management of the diabetic heart. However, the in vivo functional benefit(s) of the training programs on cardiac cycle events in diabetes are poorly understood. In this study, we used three groups of Sprague-Dawley rats (sedentary control, sedentary diabetic, and exercised diabetic) to assess the effects of endurance training on the left ventricular (LV) cardiac cycle events in diabetes. At the end of 9 wk of exercise training, noninvasive cardiac functional evaluation was performed by using high-resolution magnetic resonance imaging (9.4 T). An ECG-gated cine imaging protocol was used to capture the LV cardiac cycle events through 10 equally incremented phases. The cardiac cycle phase volumetric profiles showed favorable functional changes in exercised diabetic group, including a prevention of decreased end-diastolic volume and attenuation of increased end-systolic volume that accompanies sedentary diabetes. The defects in LV systolic flow velocity, acceleration, and jerk associated with sedentary diabetes were restored toward control levels in the trained diabetic animals. This magnetic resonance imaging study confirms the prevailing evidence from earlier in vitro and in vivo invasive procedures that exercise training benefits cardiac function in this model of diabetic cardiomyopathy despite the extreme catabolic state of the animals. cardiac cycle; diabetic cardiomyopathy; left ventricle; magnetic resonance imaging Address for reprint requests and other correspondence: Irina V. Smirnova, Dept. of Physical Therapy and Rehabilitation Science, Univ. of Kansas Medical Center, MS 2002, 3901 Rainbow Blvd., Kansas City, KS 66160 (e-mail: ismirnova{at}kumc.edu )