title: Skeletal muscle contractile protein function is preserved in human heart failure.
abstract: Skeletal muscle weakness is a common finding in patients with chronic heart failure (CHF). This functional deficit cannot be accounted for by muscle atrophy alone, suggesting that the syndrome of heart failure induces a myopathy in the skeletal musculature. To determine whether decrements in muscle performance are related to alterations in contractile protein function, biopsies were obtained from the vastus lateralis muscle of four CHF patients and four control patients. CHF patients exhibited reduced peak aerobic capacity and knee extensor muscle strength. Decrements in whole muscle strength persisted after statistical control for muscle size. Thin filaments and myosin were isolated from biopsies and mechanically assessed using the in vitro motility assay. Isolated skeletal muscle thin-filament function, however, did not differ between CHF patients and controls with respect to unloaded shortening velocity, calcium sensitivity, or maximal force. Similarly, no difference in maximal force or unloaded shortening velocity of isolated myosin was observed between CHF patients and controls. From these results, we conclude that skeletal contractile protein function is unaltered in CHF patients. Other factors, such as a decrease in total muscle myosin content, are likely contributors to the skeletal muscle strength deficit of heart failure.
authors.affiliation: Univ. of Vermont, College of Medicine, Burlington, VT 05405, USA. vanburen@physiology.med.uvm.edu
authors.forename: Yoko
authors.initials: Y
authors.lastname: Okada
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Toth
authors.forename: Peter
authors.initials: P
authors.lastname: Vanburen
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D002908:Chronic Disease; D003285:Contractile Proteins / Q000502:physiology*; D005260:Female; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D008875:Middle Aged; D018656:Muscle Fibers, Fast-Twitch / Q000502:physiology; D018657:Muscle Fibers, Slow-Twitch / Q000502:physiology; D009124:Muscle Proteins / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009210:Myofibrils / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000378:metabolism; D018994:Myosin Light Chains / Q000378:metabolism; D051381:Rats; D013318:Stroke Volume / Q000502:physiology; D019209:Troponin C / Q000378:metabolism; D019210:Troponin I / Q000378:metabolism; D020107:Troponin T / Q000378:metabolism
chemical_list: D003285:Contractile Proteins; D009124:Muscle Proteins; D018994:Myosin Light Chains; D019209:Troponin C; D019210:Troponin I; D020107:Troponin T; D018995:Myosin Heavy Chains