Fox J, Care A D
J Endocrinol. 1978 May;77(2):225-31. doi: 10.1677/joe.0.0770225.
The intestinal absorption of phosphate has been studied in conscious pigs, each prepared with a Thiry-Vella loop of jejunum. The feeding of diets low in either calcium or phosphorus caused a significant increase in the efficiency of absorption of phosphate from the solution used to perfuse the jejunal loop in both intact and parathyroidectomized (PTX) pigs. An intravenous infusion of parathyroid hormone (0.22 u. kg-1 h-1) into a PTX pig also enhanced the absorption of phosphate. The increase in the absorption of phosphate when the low phosphorus diet was fed was not caused by an increase in the concentration gradient of phosphate ions between the jejunal lumen and blood. It is concluded that the intestinal absorption of phosphate shows similar changes to those of calcium when diets low in calcium or phosphorus are fed and that parathyroid hormone, although capable of stimulating the absorption of phosphate, is not essential for this adaptation. These effects are probably brought about by changes in the renal production and mucosal uptake of 1,25-dihydroxycholecalciferol, the active metabolite of vitamin D3.
已在清醒猪身上研究了磷酸盐的肠道吸收情况，每头猪均制备有一段空肠的Thiry-Vella肠袢。给完整猪和甲状旁腺切除（PTX）猪喂食钙或磷含量低的日粮，会导致用于灌注空肠肠袢溶液中磷酸盐的吸收效率显著提高。向一头PTX猪静脉输注甲状旁腺激素（0.22单位·千克⁻¹·小时⁻¹）也会增强磷酸盐的吸收。喂食低磷日粮时磷酸盐吸收的增加并非由空肠腔与血液之间磷酸盐离子浓度梯度的增加所致。得出的结论是，当喂食钙或磷含量低的日粮时，磷酸盐的肠道吸收表现出与钙类似的变化，并且甲状旁腺激素虽然能够刺激磷酸盐吸收，但对于这种适应性变化并非必不可少。这些作用可能是由维生素D3的活性代谢物1,25-二羟胆钙化醇的肾脏生成和黏膜摄取变化引起的。
