Maltotriose and maltotetraose excreted in urine following intravenous administration of maltose to human volunteers.

To determine the extent of maltose excreted into the urine, sugar substances present in the urine following intravenous infusion of maltose were analyzed. Maltose, glucose, maltotriose and maltotetraose in the urine were detected by gas chromatography and identified by mass spectrometric analysis. The total amounts of sugar substances excreted after 10 per cent maltose solution given at three different infusion rates were calculated. The excreted amounts of maltotriose and maltotetraose increased in a dose and time dependent manner. As these compounds were not detected in the plasma either during or after the administration of maltose, the kidney probably plays a role in the biosynthesis of maltotriose and maltotetraose. Studies on the organ homogenates of the rabbit showed that the enzyme activity for the biosynthesis of maltotriose from maltose was mainly in the kidney. The glucose excreted into the urine probably originates from maltose catalyzed to glucose, mainly by the action of kidney maltase. As the rate of excretion of sugar substances increased in a dose dependent manner, adequate infusion rates of maltose should be less than 0.5 g/kg/hour.