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Estimation of the carnosine content of different fibre types in the middle gluteal muscle of the thoroughbred horse.
Author(s) -
Sewell D A,
Harris R C,
Marlin D J,
Dunnett M
Publication year - 1992
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1992.sp019310
Subject(s) - carnosine , fibre type , anserine , chemistry , myosin , medius , muscle fibre , haematoxylin , skeletal muscle , anatomy , biochemistry , medicine , biology , amino acid , immunohistochemistry , histidine
1. Skeletal muscle samples were obtained by needle biopsy from one of two depths of the m. gluteus medius in a group of twenty race‐trained thoroughbred horses. 2. The content of carnosine was determined in each muscle sample, part of which was used for histochemical analysis. Fibres were classified as type I, type IIA or type IIB on the basis of the pH dependent lability of the myosin ATPase reaction. 3. Muscle samples with a higher type II fibre section area (FSA) have a higher carnosine content than those with a higher type I FSA. 4. Multiple linear regression analysis was used to estimate the mean carnosine content of individual fibre types. The results estimated a mean carnosine content in type I fibres of 54 mmol (kg dry muscle (DM))‐1, in type IIA fibres 85 mmol (kg DM)‐1 and in type IIB fibres 180 mmol (kg DM)‐1. 5. Based on the estimated values of single fibre carnosine content, there was close concordance between the estimated and the measured carnosine content of mixed fibre samples. 6. It would appear from this and other studies that carnosine has an important role as a physico‐chemical buffer in equine middle gluteal muscle and that this is greatest in type IIB fibres, where it may account for up to 50% of physico‐chemical buffering of H+ produced by muscle in the pH range 7.1‐6.5.