Quantification of Osmotic Water Transport in vivo using Fluorescent Albumin.

• Osmotic water transport across the peritoneal membrane is applied during peritoneal dialysis to remove the excess of water accumulated in patients with end-stage renal disease. The discovery of aquaporin water channels and the generation of transgenic animals have stressed the need for novel and accurate methods to unravel molecular mechanisms of water permeability in vivo. Here we describe the use of fluorescently-labeled albumin as reliable indicator of osmotic water transport across the peritoneal membrane in a well-established mouse model of peritoneal dialysis. After detailed evaluation of the intraperitoneal tracer mass kinetics, the technique was validated against direct volumetry, considered as gold standard. The pH-insensitive dye AlexaFluor555-albumin was applied to quantify osmotic water transport across the mouse peritoneal membrane resulting from modulating dialysate osmolality and genetic silencing of the water channel AQP1. Quantification of osmotic water transport using AlexaFluor(555)-albumin closely correlated with direct volumetry and with estimations based on radio-iodinated ((125)I) serum albumin (RISA). The low intraperitoneal pressure probably accounts for the negligible disappearance of the tracer from the peritoneal cavity in this model. Taken together, these data demonstrate the appropriateness of the pH-insensitive AlexaFluor(555)-albumin as a practical and reliable intraperitoneal volume tracer to quantify osmotic water transport in vivo.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Urologi och njurmedicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Urology and Nephrology (hsv//eng)

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