Abstract 18211: Exercise-Induced Vasospasm in Skeletal Muscle of Patients With Becker Muscular Dystrophy Lacking Sarcolemmal nNOS

• Published in: Circulation (New York, N.Y.) N.Y.), 2016-11, Vol.134 (Suppl_1 Suppl 1), p.A18211-A18211
• Main Authors: Hakimi, Matthew, Hsu, Brent, Mason, O’Neil, Rosenberry, Ryan, Rader, Florian, Baresi, Rita, Lindner, Jonathan R, Victor, Ronald G
• Format: Article
• Language: English
• ISSN: 0009-7322; 1524-4539

IntroductionNeuronal nitric oxide synthase (nNOS) is the main source of nitric oxide (NO) in skeletal muscle. In mouse models of Duchenne or Becker muscular dystrophy (BMD), absence of sarcolemma localized nNOS engenders exercise-induced spasm of skeletal muscle microvessels, causing injury and fatigue. To test for exercise-induced vasospasm in human dystrophic muscle, we performed parametric analysis of skeletal muscle perfusion with contrast enhanced ultrasound to measurecapillary blood volume (A), highly regulated by NO; microvascular flux rate (β), regulated by classical resistance arteriolar tone; and muscle blood flow (Aхβ).MethodsPerfusion images of the flexor digitorum profundus were made after rhythmic handgrip (90s) at 25%, 50%, and 75% maximal voluntary contraction (MVC) in 5 unmedicated BMD patients (mean age 30 ± 3.5Y) and 10 healthy age-matched male controls (Ctrls). All patients had mutated dystrophin that cannot bind nNOS and muscle biopsy showing no antibody staining for sarcolemmal nNOS.ResultsIn Ctrls, flow (Aβ) increased more (p