Peritoneal membrane transport system

The peritoneal membrane transport system represents the physiological mechanism responsible for fluid and waste exchange during peritoneal dialysis (PD). This system is conceptualized by the 'Three-Pore Model,' which identifies three distinct pathways for transport across the peritoneal capillary endothelium: ultra-small pores (Aquaporin-1), small pores (intercellular clefts), and large pores (venular gaps) [1, 2]. Aquaporin-1 (AQP1) is the primary molecular target for water transport, facilitating approximately 50% of ultrafiltration driven by crystalloid osmotic gradients like glucose [3, 4]. Small pores allow for the diffusion of small solutes like urea and creatinine, while large pores permit the passage of macromolecules such as albumin [2]. Chronic exposure to bioincompatible dialysis fluids can lead to structural remodeling, including peritoneal fibrosis and neoangiogenesis, which results in ultrafiltration failure—a major cause of PD technique failure [1, 3]. Therapeutic interventions focus on using osmotic agents like icodextrin to bypass AQP1-mediated transport or experimental agents like SGLT2 inhibitors to preserve membrane integrity [2, 6]. Citations: [1] Rippe B. (1993) PMID: 8395256; [2] Devuyst O, et al. (2002) PMID: 12138152; [3] Morelle J, et al. (2015) PMID: 26224789; [4] Ni J, et al. (2001) PMID: 11298774; [6] Martus G, et al. (2021) PMID: 33479017.

Other names

Three-pore modelPeritoneal membrane water and solute transport pathwaysPeritoneal barrierPeritoneal transport pathways

Generation of crystalloid or colloid osmotic gradients to drive water and solute flux through specific pore populations, including Aquaporin-1 and intercellular clefts [1, 2].