The metabolism of galactose

THE immediate purpose of the work reported in this and the previous paper [Harding and Grant, 1932-33] has been to trace as far as possible, by methods of direct analysis, the fate of orally administered galactose. The use of galactose- acclimatised yeast [Harding and Grant, 1931-32] or S. marxianus [Harding, Nichaolson and Grant, 1932-33] as an analytical reagent enables free galactose in extracts or preparations of blood, urine and tissues to be estimated with precision. The previous paper showed that the oral administration of moderate amounts of galactose (40 g.) to adult man resulted in a rapid entrance ofgalactose into the blood stream, with a peak amount at 30-60 mins. followed by a fall to zero by the end of 2 hours. A small increase in arterial blood-glucose was also noted. The urine contained amounts not greater than 2 g. galactose. With this amount of galactose, all the sugar was disposed of in 2 hours, but with a larger dose (80 g.) the excretion into the urine sometimes continued until the fourth hour. No evidence was found in the blood or urine of any new reducing com- pound formed from galactose, nor did the urine show any trace of non-reducing substance which yielded galactose on hydrolysis, beyond those small, and as yet doubtful, amounts demonstrated in the fasting condition by Harding and Grant [1931-32]. The present communication traces the absorption of galactose from the intestine of the rat and its disappearance from the tissues. EXPERIMENTAL AND ANALYTICAL METHODS.