Black wildebeest skeletal muscle exhibits high oxidative capacity and a high proportion of type IIx fibres

Abstract

The aim of the study was to investigate the skeletal muscle characteristics of black wildebeest (Connochaetes gnou) in terms of fibre type and metabolism. Samples were obtained post mortem from the vastus lateralis and longissimus lumborum muscles and analysed for myosin heavy chain (MHC) content. Citrate synthase (CS), 3-hydroxyacyl co A dehydrogenase (3HAD), phosphofructokinase (PFK), lactate dehydrogenase (LDH) and creatine kinase (CK) activities were measured spectrophotometrically to represent the major metabolic pathways in these muscles. Both muscles had less than 20% MHC I, whereas MHC IIa and MHC IIx were expressed in excess of 50% in the vastus lateralis and longissimus lumborum muscles, respectively. Overall fibre size was 2675±1034 μm(2), which is small compared with other species. Oxidative capacity (CS and 3HAD) in both muscles was high and did not differ from one another, but the longissimus lumborum had significantly (P<0.05) higher PFK, LDH and CK activities. No relationships were observed between fibre type and the oxidative and oxygen-independent metabolic capacity as measured by specific enzyme activities. This study confirms the presence of both fast-twitch fibres and high oxidative capacity in black wildebeest, indicating an animal that can run very fast but is also fatigue resistant.