Diamond J M, Ehrlich B E, Morawski S G, Santa Ana C A, Fordtran J S
J Membr Biol. 1983;72(1-2):153-9. doi: 10.1007/BF01870322.
There is significant absorption of Li+ by human jejunum and ileum, but negligible absorption by human colon. Thus, a proximal-to-distal gradient of decreasing Li+ absorption and increasing junctional tightness exists in intestine as well as in renal tubule. For six leaky epithelia the relative permeabilities of K+, Na+, and Li+ by the junctional route are in the sequence PK greater than PNa greater than PLi and all fall within a factor of 2.5. In contrast, for tight epithelia PLi approximately PNa much greater than PK in the amiloride-sensitive channel of the apical membrane, but PK much greater than PLi approximately PNa in the basolateral membrane. The ability of several tight epithelia to sustain nonzero transepithelial Li+ absorption despite this basolateral barrier may be due to Na+/Li+ countertransport at the basolateral membrane, resulting in secondary active transport of Li+ across the epithelium.
人体空肠和回肠对锂离子有显著吸收，但结肠对锂离子的吸收可忽略不计。因此，在肠道以及肾小管中存在从近端到远端锂离子吸收减少和连接紧密性增加的梯度。对于六种漏性上皮，通过连接途径的钾离子、钠离子和锂离子的相对通透性顺序为PK大于PNa大于PLi，且都在2.5倍的范围内。相比之下，对于紧密上皮，在顶端膜的氨氯地平敏感通道中PLi约等于PNa远大于PK，但在基底外侧膜中PK远大于PLi约等于PNa。尽管存在这种基底外侧屏障，几种紧密上皮仍能维持非零的跨上皮锂离子吸收，这可能是由于基底外侧膜上的钠/锂逆向转运，导致锂离子通过上皮的继发性主动转运。
