Cooper B A, Peyman J
Biochim Biophys Acta. 1982 Oct 22;692(1):161-4. doi: 10.1016/0005-2736(82)90514-4.
Liposomes were impermeable to folic acid (PteGlu) and its pentaglutamate (PteGlu5), but both folates leaked from human erythrocyte ghosts at a similar rate. PteGlu5 leaking from ghosts was recovered in suspending medium. This indicates that although neither folate penetrates phospholipid membranes, both can traverse erythrocyte membranes without chemical modification. Reduced monoglutamate folate entered erythrocyte ghosts more slowly than it exited. Leakage of folate in both directions was slower than that of urate which, unlike folate, did not exit faster than it entered human erythrocyte ghosts.
脂质体对叶酸（蝶酰谷氨酸）及其五谷氨酸盐（蝶酰五谷氨酸）是不可渗透的，但两种叶酸从人红细胞影中泄漏的速率相似。从红细胞影中泄漏出来的蝶酰五谷氨酸在悬浮介质中被回收。这表明，尽管两种叶酸都不能穿透磷脂膜，但两者都可以未经化学修饰地穿过红细胞膜。还原型单谷氨酸叶酸进入红细胞影的速度比离开的速度慢。叶酸在两个方向上的泄漏都比尿酸盐慢，与叶酸不同的是，尿酸盐进入人红细胞影的速度并不比离开的速度快。
