Towards a valid technique of sampling fish muscle to determine redox substrates.

The redox substrates--lactate, malate, alpha-glycerophosphate, dihydroxy acetonephosphate and pyruvate--have been determined in liver and muscle tissue from young salmon. The redox quotients have also been calculated. The freeze clamping technique was used and reliable samples of fish muscle for the determination of lactate were obtained with the aid of a pair of pliers with a gear mechanism. It was established that the lactate content in the body muscle is in close agreement with that in the blood from rested salmon parr. The concentrations of redox substrates are in good agreement with those found in mammalian tissue. The determination of the content of glycogen in fish muscle is discussed in the light of the results obtained in this study.