Biochemical composition of muscle in normal and semistarved human subjects: relevance to anthropometric measurements

Abstract

Anthropometric methods aimed at assessing muscle size in undernourished subjects assume a constant proportionality between the mass (i.e., size) and composition (specifically protein-energy content) of this tissue. This assumption was examined in three autopsy groups: controls (n = 11, sudden traumatic death), early semistarvation (n = 6), acute preterminal disease), and chronic semistarvation (n = 34, severe weight loss over time). Results of semistarved groups were expressed relative to respective control value. Early semistarvation produced no detectable change in muscle mass, protein, or total energy content (per gram wet weight), although RNA and glycogen were -50 to -70% of control value (p less than 0.05). Chronic semistarvation caused muscle atrophy (-54.2%), but not all measured constituents were reduced to the same degree. The results were H2O--52.9%, collagen--46%, noncollagen proteins--65.3%, total lipids--40%, DNA--54.1%, RNA--81.7%, glycogen--90.3%, and total energy--59.6%. Muscle per unit mass in chronic semistarvation thus reflects relatively more H2O and less protein and energy when compared to normal tissue. About 85 to 95% of muscle protein-energy loss can be detected by anthropometric measurements of muscle size; the remaining 5 to 15% depletion of protein and energy is masked by muscle compositional changes. Proper interpretation of anthropometric data requires an understanding of these unmeasured but important compositional differences in normal and semistarved muscle.

Adaptation to low energy intakes: the responses and limits to low intakes in infants, children and adults

“…Lopes et al (1982) and others have shown that malnourished patients have increased muscle fatigability associated with the possibility of a decreased content of ATP and phosphocreatinine in skeletal muscle. Changes in the glycogen and total energy contents of skeletal muscle have been found in acute and chronic semi-starvation (Heyms®eld et al, 1982). Alterations in the ratio of slowtwitch to fast-twitch ®bres in the skeletal muscle have also been reported in undernutrition.…”

Sites of Superoxide and Hydrogen Peroxide Production by Muscle Mitochondria Assessed ex Vivo under Conditions Mimicking Rest and Exercise

“…They enabled us to assess the production of H 2 O 2 from isolated mitochondria in an ex vivo system that closely mimicked the relevant aspects of the cytosol of rat muscle cells in vivo. (60 -62, 64 -66) or that 18% of muscle wet weight is protein (66,67). Published values were corrected for plasma concentrations where appropriate and for the distribution of intracellular metabolites between cytosol and mitochondria, using the following matrix/cytosol ratios from heart and liver (or the assumed values for metabolites in parentheses): glycerol 3-phosphate, glutamine (dihydroxyacetone phosphate, taurine): 0 (68,69) (83)(84)(85)(86).…”

Increase in height during the first year after bone marrow transplantation reflecting nutritional status of children

“…They are based on assumptions made about muscle composition during malnutrition and may be inaccurate and overestimate muscle protein reserves. [20][21][22] Direct measurement of skeletal muscle by computerized tomography imaging has been more closely related to urinary creatinine excretion than anthropometric measurements. 23 Ultrasonographic measures are highly correlated with computerized tomography imaging of muscles 14 and should thus be equally valid for estimating skeletal muscle protein reserves.…”