Whole body resting and exercise-induced lipolysis in sarcopaenic patients with COPD

¹ Dept of Respiratory Medicine, NUTRIM School for Nutrition, Toxicology and Metabolism, University Hospital Maastricht, Maastricht, The Netherlands
² Dept of Endocrinology and Metabolism, Academic Medical Center, Amsterdam, The Netherlands

^* To whom correspondence should be addressed. E-mail: f.franssen{at}pul.unimaas.nl.

	Abstract

An impaired -adrenoceptor-mediated lipolysis was reported in sarcopaenic COPD patients. This could play a role in the shift in body composition towards decreased fat-free mass (FFM) and relative maintenance of fat mass (FM). Lipolysis could be affected by chronic treatment with ₂-agonists or disease-related factors. Therefore, whole body resting and exercise-induced lipolysis was investigated in sarcopaenic COPD patients with moderate disease severity.

Seven sarcopaenic COPD patients (FEV₁: 53±5%, BMI: 27.5±0.9kg·m^-2) and 7 controls matched for age, gender and BMI were studied. In addition, 6 underweight COPD patients (FEV₁: 51±5%, BMI: 20.6±0.7kg·m^-2) matched for disease severity were recruited. Lipolysis and plasma levels of catecholamines were assessed during infusion of [²H₅]glycerol at rest and during submaximal cycling exercise.

Proportional FM was comparable between sarcopaenic patients and controls, while FFM-index was significantly reduced in patients. At rest, the rate of appearance (R_a) of glycerol (4.1±0.6µmol·kgFFM^-1·min^-1 and 3.3±0.2µmol·kgFFM^-1·min^-1, respectively) was not significantly different. In underweight patients, glycerol R_a (4.3±0.5µmol·kgFFM^-1·min^-1) was also comparable. End-of-exercise lipolytic rates were not significantly different between groups. Glycerol R_a was not related to fat mass. Resting epinephrine levels were significantly increased in underweight COPD patients and were related to resting lipolysis (r=0.520, p<0.05).

Sarcopaenia in COPD patients with moderate disease severity is not characterized by abnormal lipolytic rate. Altered regulation of muscle protein turnover seems to be the trigger in the body compositional shift observed in these patients.

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