Abstract
Chronic heart failure (CHF) results in central and peripheral derangements that ultimately reduce skeletal muscle O2 delivery and impair exercise tolerance. Dietary nitrate (NO3‐) supplementation improves skeletal muscle vascular function and improves tolerance to exercise. We tested the hypothesis that NO3‐ supplementation would elevate exercising skeletal muscle blood flow (BF) and vascular conductance (VC) in CHF rats. Myocardial infarction (MI) was induced (coronary artery ligation) in young‐adult male rats. After 21‐days of recovery, rats randomly received NO3‐ rich beetroot juice (CHF+BR, n=10) or a placebo (CHF, n=10). Mean arterial pressure (MAP, carotid artery catheter) and skeletal muscle BF (radiolabeled microspheres) was measured during treadmill exercise (20 m/min, 5% grade). CHF parameters (MI size, CHF: 29 ± 3, CHF+BR: 33 ± 4%, LVEDP, CHF: 18 ± 2, CHF+BR: 18 ± 2 mmHg) and exercising MAP (CHF: 131 ± 3, CHF +BR: 128 ± 4 mmHg) were not different (P<0.05) between groups. Total hindlimb skeletal muscle BF (CHF: 95 ± 5, CHF+BR: 116 ± 9 ml/min/100g) and VC (CHF: 0.75 ± 0.05, CHF+BR: 0.90 ± 0.05) were greater (P<0.05) in BR supplemented rats. The increases in BF and VC (P<0.05) were found preferentially in muscles and muscle parts containing 蠅70% type IIb + d/x muscle fibers which resulted in a ~22% increase in total skeletal muscle BF and a 20% increase in total VC during exercise. These results provide strong evidence that dietary NO3‐ supplementation improves skeletal muscle vascular function during exercise in rats with CHF and suggest that BR may provide a novel therapeutic modality for the treatment of CHF.
 NIH HL‐108328
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