Leypoldt J K, Blindauer K M
Research Service, Veterans Affairs Medical Center, Salt Lake City, Utah.
Kidney Int. 1992 Dec;42(6):1412-8. doi: 10.1038/ki.1992.435.
The dependence of protein clearance on molecular size during peritoneal dialysis can be explained by assuming that either convection or diffusion is the major mechanism governing plasma to dialysate transport of protein. If convection is the predominant transport mechanism, then plasma-to-dialysate transport rates for protein should not decrease when the protein concentration in the instilled dialysis solution is increased. In the present study, plasma-to-dialysate transport rates for fluorescein-labeled protein tracers, alpha-lactalbumin and immunoglobulin G (IgG), were determined during a six hour isotonic exchange (25 ml/kg) in New Zealand White rabbits. The protein tracers were continuously infused into the bloodstream to keep plasma concentrations relatively constant, and transperitoneal transport rates were determined either with or without tracer protein added to the instilled dialysis solution. Plasma-to-dialysate transport rates were greater for alpha-lactalbumin than for IgG as expected based on the molecular size of these proteins. Transport rates for both alpha-lactalbumin and IgG decreased when tracer protein was added to the instilled dialysis solution. The present observations do not support convection as the major mechanism governing plasma to dialysate transport of protein during peritoneal dialysis.
在腹膜透析过程中，蛋白质清除对分子大小的依赖性可以通过假设对流或扩散是控制蛋白质从血浆转运至透析液的主要机制来解释。如果对流是主要的转运机制，那么当注入的透析液中蛋白质浓度增加时，蛋白质从血浆到透析液的转运速率不应降低。在本研究中，在新西兰白兔进行的六小时等渗交换（25 ml/kg）过程中，测定了荧光素标记的蛋白质示踪剂、α-乳白蛋白和免疫球蛋白G（IgG）从血浆到透析液的转运速率。将蛋白质示踪剂持续注入血流以保持血浆浓度相对恒定，并在注入的透析液中添加或不添加示踪剂蛋白的情况下测定经腹膜的转运速率。正如基于这些蛋白质的分子大小所预期的那样，α-乳白蛋白从血浆到透析液的转运速率高于IgG。当向注入的透析液中添加示踪剂蛋白时，α-乳白蛋白和IgG的转运速率均降低。目前的观察结果不支持对流是腹膜透析过程中控制蛋白质从血浆转运至透析液的主要机制这一观点。
