Peterson D R, Carone F A, Oparil S, Christensen E I
Am J Physiol. 1982 Feb;242(2):F112-8. doi: 10.1152/ajprenal.1982.242.2.F112.
Renal processing of glucagon and insulin was compared. Iodinated glucagon (mol wt 3,674, linear molecule) or insulin (mol wt 6,000, two chains with disulfide bonds) was microinfused into surface nephrons of the rat kidney, and the radiolabel recovered in the urine was quantified and characterized. Proximal but not distal reabsorption of both peptides was observed, and uptake varied similarly as a function of tubular length. After proximal microinfusion, [125I]glucagon was largely degraded to [125I]tyrosine in the urine, but remained intact after distal infusion. [125I]Insulin was recovered as intact peptide following both proximal and distal microinfusion. Prolonged tubular sequestration of 125I label was observed following proximal microinfusion of [125I]insulin, with efflux requiring longer than 1 h for completion. No measurable cellular sequestration of [125I]glucagon was observed. Incubation of both peptides with rabbit renal microvilli membranes resulted in enzymatic hydrolysis of [125I]glucagon but relatively little or no degradation of [125I]insulin. It is concluded that glucagon and insulin are reabsorbed in the proximal tubule by predominantly different mechanisms.
对胰高血糖素和胰岛素的肾脏处理过程进行了比较。将碘化胰高血糖素（分子量3674，线性分子）或胰岛素（分子量6000，具有二硫键的两条链）微量注入大鼠肾脏的表层肾单位，对尿液中回收的放射性标记物进行定量和特性分析。观察到两种肽在近端而非远端被重吸收，并且摄取量随肾小管长度的变化情况相似。近端微量注入后，尿液中的[125I]胰高血糖素大部分降解为[125I]酪氨酸，但远端注入后仍保持完整。近端和远端微量注入后，[125I]胰岛素均以完整肽的形式被回收。近端微量注入[125I]胰岛素后，观察到125I标记物在肾小管中长时间滞留，流出过程需要超过1小时才能完成。未观察到[125I]胰高血糖素可测量的细胞内滞留。两种肽与兔肾微绒毛膜一起孵育导致[125I]胰高血糖素发生酶解，但[125I]胰岛素降解相对较少或未降解。得出的结论是，胰高血糖素和胰岛素在近端小管中的重吸收机制主要不同。
