Effect of 6 wk of high-intensity one-legged cycling on functional sympatholysis and ATP signaling in patients with heart failure

• Published in: American journal of physiology. Heart and circulatory physiology 2018-03, Vol.314 (3), p.H616-H626
• Main Authors: Munch, Gregers W, Iepsen, Ulrik W, Ryrsø, Camilla K, Rosenmeier, Jaya B, Pedersen, Bente K, Mortensen, Stefan P
• Format: Article
• Language: English
• Subjects: Adenosine triphosphate; Adenosine Triphosphate - administration & dosage; Aerobic capacity; Aged; ATP; Bicycling; Blood flow; Conductance; Cycles; Denmark; Effects; Exercise; Exercise Therapy - methods; Exercise Tolerance - drug effects; Female; Heart; Heart diseases; Heart failure; Heart Failure - blood; Heart Failure - diagnosis; Heart Failure - physiopathology; Heart Failure - therapy; Humans; Hyperemia; Hyperemia - physiopathology; Intervention; Knee; Leg; Lower Extremity; Male; Middle Aged; Muscle Contraction; Muscle, Skeletal - blood supply; Muscle, Skeletal - innervation; Muscles; Musculoskeletal system; Patients; Regional Blood Flow; Signal transduction; Signaling; Skeletal muscle; Sodium; Sodium nitroprusside; Stroke Volume; Sympathetic Nervous System - drug effects; Sympathetic Nervous System - physiopathology; Sympathomimetics - administration & dosage; Time Factors; Training; Treatment Outcome; Tyramine; Vasoconstriction; Vasodilation; Vasodilation - drug effects; Vasodilator Agents - administration & dosage; Ventricle; Ventricular Function, Left; Walking
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00379.2017

Breathlessness during daily activities is the primary symptom in patients with heart failure (HF). Poor correlation between the hemodynamic parameters of left ventricular performance and perceived symptoms suggests that other factors, such as skeletal muscle function, play a role in determining exercise capacity. We investigated the effect of 6 wk of high-intensity, one-legged cycling (HIC; 8 × 4 at 90% one-legged cycling max) on 1) the ability to override sympathetic vasoconstriction (arterial infusion of tyramine) during one-legged knee-extensor exercise (KEE), 2) vascular function (arterial infusion of ACh, sodium nitroprusside, tyramine, and ATP), and 3) exercise capacity in HF patients with reduced ejection fraction ( n = 8) compared with healthy individuals ( n = 6). Arterial tyramine infusion lowered leg blood flow and leg vascular conductance at rest and during KEE before the training intervention in both groups ( P < 0.05) but not during KEE after the training intervention. There was no difference between groups. The peak vasodilatory response to ATP was blunted in HF patients ( P < 0.05), whereas there was no difference in ACh- and sodium nitroprusside-induced vasodilation between HF patients and healthy individuals. ACh-induced vasodilation increased in HF patients after the training intervention ( P < 0.05). HIC improved aerobic capacity in both groups ( P < 0.05), whereas only HF patients made improvements in the 6-min walking distance ( P < 0.05). These results suggest that exercise hyperemia and functional sympatholysis are not altered in HF patients and that functional sympatholysis is improved with HIC in both HF patients and healthy individuals. Moreover, these results suggest that the peak vasodilatory response to ATP is blunted in HF. NEW & NOTEWORTHY The ability to override sympathetic vasoconstrictor activity (by arterial tyramine infusion) during exercise is not different between heart failure patients and healthy individuals and is improved by high-intensity, one-legged cycling training. The peak vasodilatory response to ATP is reduced in heart failure patients.