Impaired Intrinsic Exercise Capacity Predisposes To Progressive Left Ventricular Remodeling: Role Of Mierovascular Endothelial Dysfunction And Impaired Glucose Utilization

Cardiovascular risk factors are increased with low intrinsic aerobic capacity, but the concomitant impact on the progression of left lentricular (LV) morphology and microvascular function remains unresolved. We tested the hypothesis that low intrinsic running capacity (LCR) induces progressive age-dependent LV remodeling compared to high-intrinsic running capacity (HCR), accompanied by impairments in microvascular function, glucose utilization and β-adrenergic responsiveness. Hearts and vessels isolated from female rats selectively bred for either LCR or HCR were studied at 12 and 35wks of age. Control (founder) rats were studied for comparison. Compared to HCR, LCR rats exhibited characteristics of metabolic syndrome, including impaired glucose tolerance (by 14.7±4.3%, P<0.01), elevated plasma insulin (by 61±18%, P<0.05) and bodymass at 12wks; blood glucose was not elevated until 35wks (by 25.8±4.7%, P<0.005). At 12wks of age, LCR rats exhibited LV remodeling (increased cardiomyocyte width and LV collage...