Abstract 16177: Exercise Training Improves Muscle Mechano and Metaboreflex Sensitivity in Heart Failure Patients
Background: Previous studies have demonstrated that muscle mechanoreflex and metaboreflex controls are significantly altered in heart failure (HF). We tested the hypothesis that exercise training (ET) would improve mechano and metaboreflex control of muscle sympathetic nerve activity (MSNA) in HF patients. Since the mechanoreceptors are modulated by metabolites produced by cyclooxygenase-1 and 2 (COX1 and 2) and the metaboreceptors by transient receptor potential vanilloid type 1 (TRPV1) and cannabinoid receptor (CB1), we investigated the muscle gene expression of COX1 and 2, TRPV1 and CB1 receptors in HF patients.
Methods: Thirty-four consecutive, randomized HF patients, functional class II-III NYHA, EF≤40%, peak VO2≤20ml/kg/min were divided into two groups: Exercise-trained (n=17, 56±2 years) and untrained (n=17, 54±2 years). MSNA was directly recorded from the peroneal nerve. Mechanoreceptors were activated by passive exercise and metaboreceptors by post-exercise circulatory arrest. Gene expression of COX1 and 2, prostaglandins receptor (EP1, EP2, EP3 and EP4), TRPV1 and CB1 was investigated by vastus lateralis muscle biopsy using real-time PCR. ET was performed on a cycle ergometer at moderate intensity, three 40-min session/week for 16 weeks.
Results: ET reduced resting MSNA (33±2 vs. 38±2 bursts/min, P=0.01). In addition, ET reduced MSNA responses to passive exercise (Δ= 3±0.4 vs. 5±1 bursts/min, P=0.002) and increased MNSA responses during post-exercise circulatory arrest (Δ= 6±1 vs. -2±1 bursts/min, P<0.0001). ET reduced gene expression of COX2 (P=0.04), but caused no changes in COX1. ET reduced gene expression of EP4 (P=0.01), but did not change EP1, EP2 and EP3 receptors. ET increased gene expression of TRPV1 (P=0.03) and CB1 (P=0.03) receptors. No changes in untrained HF were found.
Conclusion: ET improves muscle mechano and metaboreflex control of MSNA in chronic HF patients. In addition, this improvement seems to be associated with changes in gene expression of COX2 and EP4 receptor, and gene expression of TRPV1 and CB1 receptors, respectively. These findings suggest that the improvement in muscle mechano and metaboreflex sensitivity contributes to the reduction in MSNA in exercise-trained HF patients.
- © 2013 by American Heart Association, Inc.