Ontogeny of intestinal safety factors: lactase capacities and lactose loads.
Ontogeny of intestinal safety factors: lactase capacities and lactose loads.
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肠道安全因素的个体发育：乳糖酶能力和乳糖负荷。
DOI：
10.1152/ajpregu.1999.276.3.r753
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Diamond,J
中科院分区：
文献类型：
--
作者：
O'Connor,TP;Diamond,J
我们测量了肠道安全系数（生理容量与其负荷的比率），用于发育中的幼鼠乳糖消化。具体而言，我们评估了乳糖负荷和乳糖酶和Na+-葡萄糖协同转运蛋白（SGLT-1）的串联能力之间的定量关系。这两个能力显着增加，随着年龄的增长，在哺乳幼犬作为一个结果，增加肠道质量和维护质量特定的活动。检查的最年轻的幼仔（5天）对乳糖酶和SGLT-1的安全系数都非常高，为8-13，这可能是因为牛奶中含有乳糖酶底物而不是乳糖;然而，这也表明它们的肠道容量正在准备满足未来的需求，而不仅仅是当前的需求。到第10天（以及第15天），乳糖负荷增加导致安全系数降低，为4-6，成人肠道的典型值。SGLT-1在30天（断奶）和100天（成年）大鼠中的安全系数仅为1.0。这最初是出乎意料的，因为大多数成年肠道保持适度的储备能力超出营养负荷值，但断奶后的大鼠似乎使用后肠发酵，肠道形态和产氢测定评估，作为一个内置的储备能力。乳糖酶和SGLT-1的系列能力在个体发育过程中相互一致，并且乳糖负荷受窝仔数实验变化的影响。
We measured intestinal safety factors (ratio of a physiological capacity to the load on it) for lactose digestion in developing rat pups. Specifically, we assessed the quantitative relationships between lactose load and the series capacities of lactase and the Na+-glucose cotransporter (SGLT-1). Both capacities increased significantly with age in suckling pups as a result of increasing intestinal mass and maintenance of mass-specific activities. The youngest pups examined (5 days) had surprisingly high safety factors of 8–13 for both lactase and SGLT-1, possibly because milk contains lactase substrates other than lactose; it also, however, suggests that their intestinal capacities were being prepared to meet future demands rather than just current ones. Byday 10(and also atday 15), increased lactose loads resulted in lower safety factors of 4–6, values more typical of adult intestines. The safety factor of SGLT-1 inday 30(weanling) andday 100(adult) rats was only ∼1.0. This was initially unexpected, because most adult intestines maintain a modest reserve capacity beyond nutrient load values, but postweaning rats appear to use hindgut fermentation, assessed by gut morphology and hydrogen production assays, as a built-in reserve capacity. The series capacities of lactase and SGLT-1 varied in concert with each other over ontogeny and as lactose load was manipulated by experimental variation in litter size.