内流质子梯度对Gly-Pro在仔猪小肠跨膜转运中的驱动作用

为研究内流质子梯度对仔猪小肠中Gly-Pro跨膜转运的影响,采用放射性同位素示踪及体外孵育技术,观察在不同H＋浓度条件下,Gly-Pro在仔猪小肠刷状缘膜囊（Brush border membrane vesicles,BBMV）的跨膜转运量。结果表明：膜囊内液pH为7.5时,Gly-Pro的转运显著地受到膜囊外液pH值的影响,pH为4.5～5.5时,转运最快;其中pH为5.0时的Gly-Pro跨膜转运速度在1-20 min一直高于pH为7.5时的转运速度;内流质子梯度的存在可以显著促进Gly-Pro的转运,无内流质子梯度时,Gly-Pro的转运不受膜囊外液pH变化的影响。研究结果提示,跨膜内流质子梯度是仔猪小肠中Gly-Pro的跨膜转运的一种驱动力。

Drive of Incurrent Proton Gradient on Transport of Gly-Pro in Small Intestine of Piglets

In order to study the effects of incurrent proton gradient on transport of Gly-Pro in small intestine of piglets,radioactive isotope trace and in vitro incubation technique were used to observe the transmembrane transport of Gly-Pro in small intestinal brush border membrane vesicles(BBMV).The results showed that: When internal pH of BBMV remained 7.5,transport of Gly-Pro was optimized at an external pH 4.5-5.5;Gly-Pro transport(during 1-20 min period) was greater at an external pH 5.0 than that at 7.5;Presence of an inwardly directed proton gradient stimulated Gly-Pro transport;while in the absence of an inwardly directed proton gradient,Gly-Pro transport was not different at an external pH 5.0 as compared to a pH 7.5.It was suggested that transport of Gly-Pro into small intestinal BBMV of piglets should be driven by trans-membrane inward proton gradient.