Mechanoreflex Mediates the Exaggerated Exercise Pressor Reflex in Heart Failure

In heart failure, exercise elicits excessive increases in mean arterial pressure (MAP) and heart rate (HR). Using a novel rat model, we previously demonstrated that this exaggerated cardiovascular responsiveness is mediated by an overactive exercise pressor reflex (EPR). Although we previously determined that abnormalities in the group IV afferent neuron population (associated with the metabolic component of the reflex) initiate the development of the exaggerated EPR in heart failure, these fibers do not mediate the enhanced circulatory responses to exercise. Therefore, we hypothesized that the augmentation in EPR activity is primarily mediated by the mechanically sensitive component of the reflex (mediated predominately by activation of group III afferent fibers).