Background Osmosis drives transcapillary ultrafiltration and water removal in patients treated with peritoneal dialysis. Crystalloid osmosis, typically induced by glucose, relies on dialysate tonicity and occurs through endothelial aquaporin-1 water channels and interendothelial clefts. In contrast, the mechanisms mediating water flow driven by colloidal agents, such as icodextrin, and combinations of osmotic agents have not been evaluated.

Methods We used experimental models of peritoneal dialysis in mouse and biophysical studies combined with mathematical modeling to evaluate the mechanisms of colloid versus crystalloid osmosis across the peritoneal membrane and to investigate the pathways mediating water flow generated by the glucose polymer icodextrin.

Results In silico modeling and in vivo studies showed that deletion of aquaporin-1 did not influence osmotic water transport induced by icodextrin but did affect that induced by crystalloid agents. Water flow induced by icodextrin was dependent upon the presence of large, colloidal fractions, with a reflection coefficient close to unity, a low diffusion capacity, and a minimal effect on dialysate osmolality. Combining crystalloid and colloid osmotic agents in the same dialysis solution strikingly enhanced water and sodium transport across the peritoneal membrane, improving ultrafiltration efficiency over that obtained with either type of agent alone.

Conclusions These data cast light on the molecular mechanisms involved in colloid versus crystalloid osmosis and characterize novel osmotic agents. Dialysis solutions combining crystalloid and colloid particles may help restore fluid balance in patients treated with peritoneal dialysis.

背景渗透在腹膜透析治疗的患者中推动了毛细血管超滤和水分去除。通常由葡萄糖引起的晶体渗透取决于透析液的张力，并通过内皮水通道1水通道和内皮间裂发生。相反，尚未评估介导由诸如艾考糊精之类的胶体试剂驱动的水流的机制以及渗透剂的组合。

方法我们使用了小鼠腹膜透析的实验模型和生物物理研究，并结合数学模型来评估胶体与晶体渗透穿过腹膜的机制，并研究介导葡萄糖聚合物艾考糊精产生水流的途径。

结果 计算机模拟和体内研究表明，aquaporin-1的缺失并不影响由艾考糊精诱导的渗透水运输，但确实影响了由结晶剂诱导的渗透水运输。由艾考糊精诱导的水流取决于大的胶体部分的存在，其反射系数接近于一，扩散能力低，对透析液重量摩尔渗透压浓度的影响最小。在相同的透析溶液中结合晶体渗透剂和胶体渗透剂，可显着增强水和钠在整个腹膜中的转运，与仅使用任何一种渗透剂相比，提高了超滤效率。

结论这些数据阐明了胶体与晶体渗透有关的分子机制，并表征了新型渗透剂。结合晶体和胶体颗粒的透析溶液可以帮助腹膜透析患者恢复体液平衡。