Baumrucker C R
J Dairy Sci. 1984 Nov;67(11):2500-6. doi: 10.3168/jds.S0022-0302(84)81606-9.
Cationic amino acid transport (arginine and lysine) into bovine mammary tissue occurs by a sodium independent and saturable mediated system. Concentrative uptake ratios (cell concentration/media concentration) for both arginine and lysine varied between 6 and 22. High concentrations of specific inhibitors of the neutral amino acid transport systems had no effect upon arginine or lysine uptake. Both arginine and lysine were strong inhibitors of each others uptake, whereas ornithine showed less specificity for inhibition of arginine and lysine uptake. In the presence of all amino acids, cationic amino acid uptake occurred at a rate equivalent to that with cationic substrates alone. The presence of the independent cationic amino acid transport system in bovine mammary tissue accounts for the high cationic amino acid uptake by measuring arteriovenous differences of plasma across the bovine mammary gland. This transport system is responsible for excess uptake (beyond milk protein synthesis requirements) of cationic amino acids for catabolism to other amino acids or potential oxidation.
阳离子氨基酸（精氨酸和赖氨酸）进入牛乳腺组织是通过一种不依赖钠且可饱和的介导系统进行的。精氨酸和赖氨酸的浓缩摄取率（细胞浓度/培养基浓度）在6至22之间变化。中性氨基酸转运系统的高浓度特异性抑制剂对精氨酸或赖氨酸的摄取没有影响。精氨酸和赖氨酸都是彼此摄取的强抑制剂，而鸟氨酸对精氨酸和赖氨酸摄取的抑制特异性较低。在所有氨基酸存在的情况下，阳离子氨基酸的摄取速率与仅存在阳离子底物时相当。通过测量牛乳腺组织血浆的动静脉差异，牛乳腺组织中独立的阳离子氨基酸转运系统解释了阳离子氨基酸的高摄取量。该转运系统负责阳离子氨基酸的过量摄取（超出乳蛋白合成需求），用于分解代谢为其他氨基酸或潜在的氧化。
