Microphotometry of single fibres from the quadriceps muscle in man

Abstract

Two main types of muscle fibres were histochemically identified in the lateral portion of the human quadriceps muscle. Muscle samples were obtained by needle biopsies from a highly trained, a hypotrophied and a normal leg. Serial sections were histochemically stained for myofibrillar ATPase (pH 9.4, preincubation at pH 10.3), nicotinamide adenine dinucleotide tetrazolium oxidoreductase (NADHTR) and α-glycerophosphate dehydrogenase (α-GPD, E.C.1.1.2.1.). In the two fibre types identified in the ATPase stained sections, type I (ATPase negative) and type II (ATPase positive), microphotometry was used to quantify the oxidative (NADHTR) and glycolytic (α-GPD) enzyme activity of the single fibre. The correspondence to the ATPase ‘type’ was 100% when the activity of both metabolic enzymes were combined as a ‘metabolic profile’ for each fibre. This clear distinction was unaffected by the training state of the muscle. It is concluded that histochemical reaction for myofibrillar ATPase as well as the combination of quantified NADHTR and α-GPD activity reveals the same distinct separation of human muscle fibres in two main types. The microphoto-metric technique seems useful on histochemically treated muscle sections when quantitation in each fibre type is essential as, e.g. in relation to specific illness or training.

Key Words:

• α-glycerophosphate dehydrogenase (E.C.1.1.2.1.)
• distributional error
• human muscle fibre types
• human muscle fibre areas
• muscle histochemistry
• NADH tetrazolium oxidoreductase