Biochemistry of sheep tissues. Enzyme systems of liver, brain and kidney

Little information is available on the enzyme activities of sheep tissues in vitro. However, Krebs (1950), using more refined and standardized techniques, has shown that, although the QO, values of the tissues of larger animals are lower than the corresponding values for smaller species, there is no direct relationship to the basal heat production of the intact aninal. The QO value for most tissues changes much less with body weight than does the rate of heat production. Krebs attributed the differences in basal heat production in animals of different size mainly to variation in the QO of muscle, and suggests that the metabolic rate of other tissues is govemed by the specific energy requirements of the particular tissue and not by the heat requirements of the whole body. Comparative Qo3 values from various tissues and species, in- cluding sheep, are published by Krebs (1950) and Albritton (1954). These figures are of general interest but cannot supply information on the activities of isolated enzyme systems. More specific data are available on the metabolism of short- chain fatty acids by sheep-rumen epithelium and slices of kidney and liver (Pennington, 1952, 1954;