A twoto threefold increase in guinea pig liver creatine occurs within 24 hr. after the withdrawal of food. 2. In rats the increase in liver creatine is less marked, but a pronounced creatinuria occurs coincident with a fall in blood sugar to 60-70 mg./ 100 ml. 3. Perfusion experiments have demonstrated that rat skeletal muscle creatine is reversibly sensitive to blood sugar levels. 4. The relation between creatine distribution, carbohydrate metabolism and electrolyte balance is discussed. We are indebted to Professor J. H. Burn for advice and for extending to us the facilities of his Department, to Drs Coxon, Fisher and Parsons for much helpful discussion and to Mrs Lawrence for providing us with hypophysecto. mized rats. We should also like to thank Miss M. Cole and Mrs J. Kingerlee for skilled technical assistance.
1. Glucuronide synthesis from uridine diphosphate glucuronate and o-aminophenol or p-nitrophenol in the presence of uridine diphosphate transglucuronylase of mouse-liver homogenates has been studied with respect to inhibition by compounds known to be conjugated under the experimental conditions, and also by thiophenol. 2. Raising the o-aminophenol concentration decreased the inhibition of o-aminophenyl glucuronide synthesis by the alternative glucuronyl acceptors phenol, menthol and benzoic acid, but was without effect on that caused by p-nitrophenol and thiophenol. 3. Raising the p-nitrophenol concentration decreased or abolished the inhibition of p-nitrophenyl glucuronide synthesis due to phenol, menthol, benzoic acid, anthranilic acid, o-aminophenol and thiophenol. 4. The o-aminophenol system was much more readily inhibited by all compounds than the p-nitrophenol system. 5. In tris buffer, pH7.4, over 30% activation of the o-aminophenol system was achieved by 2mm-Mg(2+), but 10mm-Mg(2+) was inhibitory. The p-nitrophenol system showed only inhibition from 2mm-Mg(2+) upwards. 6. The results are discussed as suggesting that there are at least two uridine diphosphate transglucuronylases.
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