Na+ gradient-dependent transport of hypoxanthine by calf intestinal brush border membrane vesicles
Na+ gradient-dependent transport of hypoxanthine by calf intestinal brush border membrane vesicles
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小牛小肠刷状缘膜囊泡对次黄嘌呤的Na梯度依赖性转运
DOI：
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
E. Scharrer
中科院分区：
文献类型：
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作者：
A. Theisinger;B. Grenacher;E. Scharrer
从小牛空肠近端和远端分离纯化刷状缘膜囊泡，研究次黄嘌呤的转运特性。次黄嘌呤在囊泡中的摄取受到跨膜Na+梯度和内部负电位的刺激，导致囊泡内次黄嘌呤的瞬时积累，尤其是在空肠近端。Na+依赖的次黄嘌呤摄取可能通过两个可饱和的转运系统发生，一个是高亲和力(Km=0.33mol/μL)的转运体，另一个是低亲和力(Km=165nμ/L)的转运体。鸟嘌呤、次黄嘌呤、胸腺嘧啶和尿嘧啶抑制囊泡内次黄嘌呤摄取，而腺嘌呤和核苷肌苷、胸腺嘧啶核苷则无抑制作用。这些发现首次证明了肠道刷状缘膜囊泡中主动的Na+梯度依赖的核碱基转运。
The properties of hypoxanthine transport were investigated in purified brush border membrane vesicles isolated from calf proximal and distal jejunum. Hypoxanthine uptake in the vesicles was stimulated by a transmembrane Na+ gradient and an inside negative potential resulting in a transient accumulation of intravesicular hypoxanthine, especially in the proximal jejunum. Na+-dependent hypoxanthine uptake at this site seemed to occur by two saturable transport systems, a high affinity (Km=0.33 μmol/l) and a low affinity (Km=165 μmol/l) transporter. Guanine, hypoxanthine, thymine and uracil inhibited intravesicular hypoxanthine uptake, whereas adenine and the nucleosides inosine and thymidine were without effect. These findings represent the first demonstration of active Na+ gradient-dependent nucleobase transport in intestinal brush border membrane vesicles.
人肠刷状缘膜中钠依赖性核苷转运。
DOI：
10.1152/ajpgi.1997.272.6.g1314
发表时间：
1997
期刊：
The American journal of physiology
影响因子：
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作者：
Patil,SD;Unadkat,JD
通讯作者：
Unadkat,JD