Calvert D T, Shennan D B
Hannah Research Institute, UK.
J Dairy Res. 1996 Feb;63(1):25-33. doi: 10.1017/s0022029900031514.
The transport of lysine by perfused lactating rat mammary tissue has been examined using a rapid, paired-tracer dilution technique. This experimental approach allowed the characteristics of lysine transport across the blood-facing aspect of the mammary epithelium to be studied. The clearance of lysine from the perfusate was influenced by the extracellular lysine concentration in a fashion consistent with the presence of carrier-mediated transport. Replacing extracellular Na+ with N-methyl-D-glucamine had no significant effect on lysine transport. Lysine uptake was inhibited by extracellular leucine and glutamine but not by alpha-(methylamino)isobutyric acid. Leucine interacted with lysine transport under Na+(-)free conditions. It appears that the system for cationic acid transport which is situated in the blood-facing aspect of the lactating rat mammary epithelium may also accept neutral amino acids as substrates.
利用一种快速的、成对示踪剂稀释技术，对灌流的泌乳大鼠乳腺组织中赖氨酸的转运进行了研究。这种实验方法使得能够研究赖氨酸跨乳腺上皮面向血液一侧的转运特性。灌流液中赖氨酸的清除受到细胞外赖氨酸浓度的影响，其方式与载体介导转运的存在相一致。用N-甲基-D-葡萄糖胺取代细胞外的Na+对赖氨酸转运没有显著影响。赖氨酸摄取受到细胞外亮氨酸和谷氨酰胺的抑制，但不受α-（甲基氨基）异丁酸的抑制。在无Na+条件下，亮氨酸与赖氨酸转运相互作用。看来位于泌乳大鼠乳腺上皮面向血液一侧的阳离子酸转运系统也可能接受中性氨基酸作为底物。
