Bereket G, Lin J J, Bereket A, Lang C H, Kaskel F J
Department of Pediatrics, Baskent University, Ankara, Turkey.
Pediatr Nephrol. 1998 Sep;12(7):581-8. doi: 10.1007/s004670050510.
The kinetics of peritoneal transport of insulin-like growth factor (IGF) system-related proteins during dialysis is not well characterized. We studied temporal changes in dialysate and serum concentrations of IGF-I and IGF-II as well as IGF binding protein (BP)-1, -2, and -3 in ten children with end-stage renal disease (ESRD) undergoing continuous cycling peritoneal dialysis (CCPD) during a 4-h peritoneal equilibration test (PET). Dialysate concentrations of IGF-I, IGF-II, and all three IGFBPs demonstrated a time-dependent increase during PET. Despite their transport, the serum concentrations of these proteins did not change significantly during the PET. Dialysate/serum ratios for IGF-I, IGF-II, and IGFBP-1, -2, and -3 were significantly increased at 2 h and increased further at 4 h, at which time values averaged 1.3+/-0.2%, 3.1+/-0.5%, 6.2+/-1.0%, 2.4+/-0.2%, and 1.3+/-0.2% of serum levels, respectively. The transperitoneal clearance (microl/min per 1.73 m2) of the three IGFBPs was inversely related to both their molecular weight and plasma concentration. However, peritoneal clearance of IGF-I and -II was similar to that of the larger and more-abundant IGFBP-3. Mass transfer rates (microg/h per 1.73 m2) for the IGFs and their binding proteins were directly proportional to their prevailing plasma concentration. Based on estimates of mass transfer, only a small molar excess of IGFBPs was removed from the circulation relative to the combined molar concentration of IGF-I and IGF-II. Hence, it seems unlikely that any beneficial effect of CCPD on growth in children with ESRD is mediated via a preferential loss of IGFBPs into the dialysate fluid.
透析期间胰岛素样生长因子（IGF）系统相关蛋白的腹膜转运动力学尚未得到充分表征。我们研究了10名终末期肾病（ESRD）儿童在4小时腹膜平衡试验（PET）期间进行持续循环腹膜透析（CCPD）时，透析液和血清中IGF-I、IGF-II以及IGF结合蛋白（BP）-1、-2和-3的浓度随时间的变化。在PET期间，透析液中IGF-I、IGF-II以及所有三种IGFBPs的浓度均呈现出时间依赖性增加。尽管这些蛋白能够转运，但在PET期间其血清浓度并未发生显著变化。IGF-I、IGF-II以及IGFBP-1、-2和-3的透析液/血清比值在2小时时显著升高，并在4小时时进一步升高，此时其值分别平均为血清水平的1.3±0.2%、3.1±0.5%、6.2±1.0%、2.4±0.2%和1.3±0.2%。三种IGFBPs的经腹膜清除率（每1.73 m²微升/分钟）与其分子量和血浆浓度均呈负相关。然而，IGF-I和-II的腹膜清除率与更大且更丰富的IGFBP-3相似。IGF及其结合蛋白的物质转运速率（每1.73 m²微克/小时）与其当时的血浆浓度成正比。基于物质转运的估计，相对于IGF-I和IGF-II的联合摩尔浓度，仅有少量摩尔过量的IGFBPs从循环中被清除。因此，CCPD对ESRD儿童生长的任何有益作用似乎不太可能是通过IGFBPs优先丢失到透析液中介导的。
