Impaired oxidative metabolism increases adenine nucleotide breakdown in McArdle's disease

K. Sahlin, N. H. Areskog, R. G. Haller, K. G. Henriksson, L. Jorfeldt, S. F. Lewis

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

Two patients with muscle phosphorylase deficiency [McArdle's disease (McA)] were studied during bicycle exercise at 40 (n = 2) and 60 W (n = 1). Peak heart rate was 170 and 162 beats/min, corresponding to ~90% of estimated maximal heart rate. Muscle samples were taken at rest and immediately after exercise from the quadriceps femoris. Lactate content remained low in both muscle and blood. Acetylcarnitine, which constitutes a readily available form of acetyl units and thus a substrate for the tricarboxylic acid cycle, was very low in McA patients both at rest and during exercise, corresponding to ~17 and 11%, respectively, of that in healthy subjects. Muscle NADH was unchanged during exercise in McA patients in contrast to healthy subjects, in whom NADH increases markedly at high exercise intensities. Despite low lactate levels, arterial plasma NH3 and muscle inosine 5'-monophosphate increased more steeply relative to work load in McA patients than in healthy subjects. The low postexercise levels of lactate, acetylcarnitine, and NADH in McA patients support the idea that exercise performance is limited by the availability of oxidative fuels. Increases in muscle inosine 5'-monophosphate and plasma NH3 indicate that lack of glycogen as an oxidative fuel is associated with adenine nucleotide breakdown and increased deamination of AMP. It is suggested that the early onset of fatigue in McA patients is caused by an insufficient rate of ADP phosphorylation, resulting in transient increases in ADP.

Original languageEnglish (US)
Pages (from-to)1231-1235
Number of pages5
JournalJournal of applied physiology
Volume69
Issue number4
DOIs
StatePublished - 1990

Keywords

  • acetylcarnitine
  • adenosine 5'-diphosphate
  • adenosine 5'-monophosphate
  • adenosine 5'-triphosphate
  • exercise
  • inosine 5'-monophosphate
  • redox state

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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