NICOTINAMIDE NUCLEOTIDE COENZYMES AND GLUCOSE METABOLISM IN THE LIVERS OF FOETAL AND NEWBORN LAMBS

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Abstract
Specific enzymic reactions were used to determine the concentration of both oxidized and reduced nicotinamide nucleotide coenzymes in the livers of fetal, newborn and young lambs and of adult sheep. The relationship between the rate of change of number of nuclei as a function of the rate of change of the amount of nicotinamide nucleotide coenzymes/nucleus during liver growth (Caiger et al. 1962) was confirmed. The rates of reduction of nicotinamide adenine dinucleotide phosphate (NADP) in the presence of glucose 6-phosphate, 6-phosphogluconate and glucose plus adenine triphosphate (ATP) were determined in liver homogenates. In each case these rates decreased during development of the lambs. Deoxyribo-nucleic acid (DNA) P was determined in the livers of lambs and sheep and gave a mean value of 1-12 [mu][mu]g of DNA P/nucleus (range 0-93-1-30 [mu][mu]g in 19 animals). The coenzyme ratio ([NAD] +[NADH2]):([NADP] + [NADPH2]) fell from 6-10 in the livers of prenatal and newborn lambs; to 2-3 in older lambs and adult sheep. These findings are discussed with reference to the growth and intermediary metabolism of the liver in lambs and sheep.