[Mechanisms of interaction of vitamins B1 and PP during absorption in rat intestine]

Interrelation between vitamins B1 and PP during absorption in rat intestinum tenue depended on the quantitative ratio of vitamins in luminal contents. Large doses of one of vitamins decreased absorption of physiologic doses of another drug affecting vitamin metabolism in intestinal wall. Excess of nicotinic acid (40-10(-3)M) inhibited thiamine pyrophosphatase activity in intestinal mucosa if thiamine was used at concentration 3-1-10(-6) M). Use of low amount of 14C-nicotinic acid (40-10(-6) M) caused an occurrence of 14C-nicotinamide in intestinal mucosa; content of nicotinamide was distinctly decreased, when 14C-nicotinic acid was administered simultaneously with 3-1-10(-3) M thiamine. tat the same time, thiamine did not effect on 14C-nicotinic acid accumulation in segments of rat intestinum tenue in vitro.