Muscle fibers, ubiquinone and exercise capacity in effort angina.

Seventeen male patients with ischaemic heart disease (IHD) and effort angina performed OBLA exercise stress tests (set to 2.0 mmol x l-1). They had muscle biopsies from the vastus lateralis muscle the day before coronary by-pass grafting, and from the internal and external intercostal, diaphragm and gastrocnemius muscles during surgery. They had a low WOBLA (83 +/- 6 W, mean +/- 1 S.E.M), WOBLA corresponded to 79 +/- 4% (% WOBLA) of WSL (symptom limited or 'maximal' capacity = 111 +/- 11 W). Peak blood lactate concentration averaged 2.9 mmol x l-1. Muscle fibre composition disclosed a depressed percent slow twitch (ST or 'red') muscle fibres in the vastus lateralis and intercostal muscles (%ST). The diaphragm and gastrocnemius muscles had normal %ST. Intercostal muscles had elevated values for the fast twitch muscle fibre (FT) subgroup FTa indicative of endurance adaptation. The vastus lateralis, gastrocnemius and diaphragm muscles had normal muscle ubiquinone (UQ) contents, whereas the intercostals were depleted. Plasma contents of the antioxidants UQ and alpha-tocopherol were low as compared to healthy man.