Abstract: FR-PO584

Functional Sympatholysis Is Impaired in Chronic Renal Disease

Session Information

Category: Hypertension

  • 1101 Hypertension: Basic and Experimental - Neural and Inflammatory Mechanisms

Authors

  • Downey, Ryan M, Emory University School of Medicine, Atlanta, Georgia, United States
  • Liao, Peizhou, Emory University Rollins School of Public Health, Atlanta, Georgia, United States
  • Dacosta, Dana, Emory University School of Medicine, Atlanta, Georgia, United States
  • Park, Jeanie, Emory University School of Medicine, Atlanta, Georgia, United States
Background

Chronic renal failure is characterized by exercise intolerance. Although exercise induces reflex activation of sympathetic nerve activity (SNA), local metabolites within exercising skeletal muscle oppose SNA-mediated vasoconstriction, preserving blood flow and oxygenation to the working muscle, termed functional sympatholysis. We hypothesized that compared to healthy controls (CON), hypertensives without kidney disease (HTN), chronic kidney disease (CKD) and end-stage renal disease (ESRD) patients have impaired functional sympatholysis.

Methods

Muscle oxygen tissue saturation index (TSI) was measured using near-infrared spectroscopy (NIRS) of the forearm in 46 subjects (10 CON, 8 HTN, 12 CKD, 12 ESRD). Sympathetic activation was induced using lower-body negative pressure (LBNP). Continuous muscle TSI was measured at rest, during LBNP, and during LBNP with concomitant rhythmic handgrip exercise at 30% of maximum voluntary contraction.

Results

Baseline muscle TSI was significantly lower in HTN, CKD, and ESRD compared to CON (CON, 69.30±1.86%; HTN, 65.74±1.94%; CKD, 66.88±1.08%; ESRD, 62.79±1.60%; p=0.042). Muscle TSI decreased in all groups during SNS activation induced by LBNP at rest. When compared to muscle TSI changes during LBNP at rest, the reduction in muscle TSI was significantly ameliorated during LBNP with handgrip exercise in CON (-11.94±2.04% vs. -6.25±1.82%, p=0.011), demonstrating intact functional sympatholysis.

Conclusion

There was no significant improvement in muscle TSI during LBNP with concomitant exercise in HTN, CKD or ESRD suggesting impaired functional sympatholysis that could contribute to exercise intolerance.

Exercise significantly attenuated the LBNP-induced decrease in TSI in healthy controls, indicating functional sympatholysis (p=0.011). Exercise did not significantly attenuate LBNP-induced decreases in TSI in hypertensive, CKD, nor ESRD groups, indicating impaired sympatholysis.

Funding

  • Other NIH Support