Middleton H M
Am J Clin Nutr. 1980 Oct;33(10):2168-73. doi: 10.1093/ajcn/33.10.2168.
The effect of vitamin B6 deficiency on the uptake and metabolism of pyridoxine x HCl by rat jejunum was studied in vitro utilizing everted sacs. Rats were studied in three grops: control, B6-replenished, and B6-deficient. Plasma and jejunal tissue pyridoxal phosphate levels in deficient rats were profoundly depressed compared to control and replenished groups. Uptake and phosphorylation rates for pyridoxine x HCl were similar among the three groups. Jejunal pyridoxal phosphate levels were unchanged after incubation of sacs from control and replenished rats for 30 min in 2 and 20 micro M pyridoxine x HCl under low phosphate (1.1 mM) conditions. Jejunal pyridoxal phosphate significantly increased, however, during similar 30-min incubations in sacs of deficient rats under low phosphate conditions and in control sacs under high phosphate (80 mM) conditions. Conclusions are 1) in vitro uptake and phosphorylatin remain intact during vitamin B6 deficiency; 2) jejunal pyridoxal phosphate is maintained at a constant level in sacs from control and replenished rats in spite of ongoing uptake and phosphorylation of pyridoxine; 3) jejunal pyridoxal phosphate significantly increases during incubationin sacs from vitamin B6-deficient rats; and 4) absorbed pyridoxine can serve directly as the source for this increase.
利用外翻肠囊体外研究了维生素B6缺乏对大鼠空肠摄取和代谢盐酸吡哆醇的影响。将大鼠分为三组进行研究：对照组、补充B6组和缺乏B6组。与对照组和补充组相比，缺乏组大鼠血浆和空肠组织中的磷酸吡哆醛水平显著降低。三组之间盐酸吡哆醇的摄取率和磷酸化率相似。在低磷酸盐（1.1 mM）条件下，将对照组和补充组大鼠的肠囊在2和20 μM盐酸吡哆醇中孵育30分钟后，空肠磷酸吡哆醛水平未发生变化。然而，在低磷酸盐条件下，缺乏组大鼠肠囊孵育30分钟期间以及在高磷酸盐（80 mM）条件下对照组肠囊孵育期间，空肠磷酸吡哆醛显著增加。结论如下：1）在维生素B6缺乏期间，体外摄取和磷酸化保持完整；2）尽管存在吡哆醇的持续摄取和磷酸化，但对照组和补充组大鼠肠囊中的空肠磷酸吡哆醛水平保持恒定；3）维生素B6缺乏组大鼠肠囊孵育期间，空肠磷酸吡哆醛显著增加；4）吸收的吡哆醇可直接作为这种增加的来源。
