参与铁转运蛋白的肉鸡原位结扎小肠肠袢铁吸收动力学

Kinetics of iron absorption by in situ ligated small intestinal loops of broilers involved in iron transporters.

作者信息

Zhang L Y, Liao X D, Zhang L Y, Lu L, Luo X G

出版信息

J Anim Sci. 2016 Dec;94(12):5219-5229. doi: 10.2527/jas.2016-0713.

DOI:10.2527/jas.2016-0713

Abstract

Two experiments were conducted with 28-d-old commercial male broilers to study the kinetics of iron (Fe) absorption and the effect of Fe treatment on divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1) mRNA levels in in situ ligated segments from different small intestinal regions of broilers. In Exp. 1, we compared Fe absorption in 3 small intestinal segments at different post-perfusion time points after perfusion with 0.45 m of Fe as Fe sulfate (FeSO ∙ 7HO), and found that the Fe absorption in the duodenum at 30, 45, and 60 min was greater ( < 0.006) than that in the jejunum, and at 60 min, the Fe absorption in the duodenum was greater ( = 0.034) than that in the ileum. In addition, the Fe absorption at 30 min was more than 85.0% of the maximum absorption in each segment. In Exp. 2, a kinetic study of Fe absorption was performed with the duodenal, jejunal, and ileal loops perfused with solutions containing 0 (control), 0.11, 0.22, 0.45, 0.80, 1.79, or 3.58 m of Fe as FeSO 7HO. The Fe concentrations in perfusates were measured at 30 min after perfusion, and in the control group and the group treated with 0.45 m Fe as FeSO 7HO, the DMT1 and FPN1 mRNA levels in the ligated duodenum, jejunum, and ileum were analyzed. The kinetic curves of Fe absorption showed that Fe absorption in the duodenum and jejunum depended on a saturated carrier-mediated process. The maximum absorption rate in the duodenal segment was greater ( < 0.0001) than that in the jejunum (42.75 vs. 8.16 nmol × cm × min), and the Michaelis-Menten constant value was higher ( < 0.0001) in the duodenum than in the jejunum (6.16 vs. 1.31 m). In the ileum, however, the Fe absorption was a non-saturated diffusion process, and the diffusive constant was 3.54 × 10 cm × min. The DMT1 and FPN1 mRNA levels in the duodenum were greater ( < 0.0001) than those in the jejunum and ileum, and greater ( < 0.009) in the jejunum than in the ileum. No differences ( > 0.25) were detected in the DMT1 and FPN1 mRNA levels of the duodenum or jejunum and the DMT1 mRNA level of the ileum between the control and the 0.45 m Fe group, but Fe perfusion increased ( < 0.03) FPN1 mRNA level in the ileum. The above results indicate that the duodenum is the main site of Fe absorption in the small intestine of broilers, and Fe absorption in the duodenum and jejunum is a saturated carrier-mediated process, but a non-saturated diffusion process in the ileum.

摘要

进行了两项试验，以28日龄的商品代雄性肉鸡为对象，研究铁（Fe）吸收动力学以及铁处理对肉鸡不同小肠区域原位结扎肠段中二价金属转运蛋白1（DMT1）和铁转运蛋白1（FPN1）mRNA水平的影响。在试验1中，灌注0.45 mmol/L硫酸亚铁（FeSO₄∙7H₂O）后，在不同灌注时间点比较了3个小肠段的铁吸收情况，发现十二指肠在30、45和60分钟时的铁吸收量高于空肠（P<0.006），且在60分钟时，十二指肠的铁吸收量高于回肠（P = 0.034）。此外，30分钟时各肠段的铁吸收量超过最大吸收量的85.0%。在试验2中，对十二指肠、空肠和回肠肠袢灌注含0（对照）、0.11、0.22、0.45、0.80、1.79或3.58 mmol/L硫酸亚铁（FeSO₄∙7H₂O）的溶液，进行铁吸收动力学研究。灌注30分钟后测定灌注液中铁浓度，并分析对照组和灌注0.45 mmol/L硫酸亚铁（FeSO₄∙7H₂O）组结扎的十二指肠、空肠和回肠中DMT1和FPN1 mRNA水平。铁吸收动力学曲线表明，十二指肠和空肠中的铁吸收依赖于饱和载体介导过程。十二指肠段的最大吸收速率高于空肠（P<0.0001）（42.75对8.16 nmol·cm⁻²·min⁻¹），十二指肠的米氏常数高于空肠（P<0.0001）（6.16对1.31 mmol/L）。然而，回肠中的铁吸收是一个非饱和扩散过程，扩散常数为3.54×10⁻⁴ cm·min⁻¹。十二指肠中DMT1和FPN1 mRNA水平高于空肠和回肠（P<0.0001），空肠中高于回肠（P<0.009）。对照组和0.45 mmol/L铁组十二指肠或空肠的DMT1和FPN1 mRNA水平以及回肠的DMT1 mRNA水平未检测到差异（P>0.25），但铁灌注增加了回肠中FPN1 mRNA水平（P<0.03）。上述结果表明，十二指肠是肉鸡小肠中铁吸收的主要部位，十二指肠和空肠中的铁吸收是饱和载体介导过程，而回肠中是一个非饱和扩散过程。