Studies on the Metabolism of Nicotinic Acid in the Sheep

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Abstract
There is no essential difference in the nicotinic acid level of the blood of lambs fed a diet low in nicotinic acid and those fed a stock diet. Lambs restricted to the deficient diet for several months continue to excrete in their urine approximately as much nicotinic acid as those on a stock diet. Subjecting the urine of normal animals to alkaline hydrolysis increased the nicotinic acid values 21.5%. Since the increase after the ingestion of a single large dose of nicotinic acid is much smaller, it appears that only a relatively small percentage is conjugated in the body under these conditions. Following the ingestion of a single large dose of nicotinic acid 42.7 to 92.2% was recovered in the urine. Fifty hours after the ingestion of a large dose of nicotinic acid the amount in the liver was materially augmented. The extent of this increase appears to bear some relationship to the amount excreted. Following the ingestion of a massive dose the nicotinic acid level of the blood increases severalfold. This rapid increment and the subsequent decline parallels closely the rate of urinary excretion.