VALIDATION OF CREATINE, GLYCOGEN AND L-(-LACTATE DETERMINATION IN BIOPSY SAMPLES OF BOVINE MUSCULUS-DIAPHRAGMA())

Whereas reliable measurements of diaphragmatic force and electrical ac tivity are now available in calves, evidence that substrate contents i n the bovine diaphragm can be accurately measured is still lacking. Th e purposes of the present study were therefore a) to describe and test the reliability of methods and procedures used for sampling, lyophili sation, extraction and dosage of muscular lactate, glycogen and creati ne contents and b) to report the variation in their levels found along the bovine diaphragm and among individuals. The repeatability of the results yielded by a) assaying the extracts, b) processing and assayin g the extracts and c) taking samples at different sites in the muscle was assessed. Neither assay, nor processing effects were significant ( P less than or equal to 0.05). Substrates were found to be homogeneous ly distributed within the two muscles studied. Substrate contents expr essed per unit of muscle weight or total creatine were neither more or less variable than when expressed per unit of dry matter.