Dextran modulates microvascular permeability: effect in isotonic and hypertonic solutions

Area of Science:

• Physiology
• Pharmacology
• Fluid Resuscitation

Background:

• Hypertonic saline solutions with Dextran (HSD) are used for rapid intravascular volume restoration.
• Dextran is believed to prolong the effects of hypertonic saline by retaining water in the vascular space.
• The precise mechanism by which Dextran modulates microvascular permeability remains to be fully elucidated.

Purpose of the Study:

• To investigate the microvascular permeability-modulating effects of Dextran in both isotonic and hypertonic solutions.
• To determine if Dextran decreases hydraulic permeability (Lp) in microvessels.
• To assess the impact of varying Dextran concentrations on microvascular barrier function.

Main Methods:

• Utilized the modified Landis micro-occlusion technique on single rat mesenteric venules.
• Perfusion with normal Ringers (NR) or hypertonic saline (HS) solutions.
• Sequential addition of 1%, 2%, and 3% Dextran to NR and HS perfusion solutions, measuring Lp at each concentration.

Main Results:

• Dextran significantly decreased hydraulic permeability (Lp) in both isotonic and hypertonic solutions.
• The permeability-reducing effect of Dextran was more pronounced in hypertonic saline solutions.
• Concentrations of 2% and 3% Dextran markedly reduced Lp, demonstrating Dextran's oncotic potential and ability to retain vascular water.

Conclusions:

• Dextran addition to both isotonic and hypertonic solutions decreases microvessel permeability.
• Dextran's ability to reduce microvascular permeability is enhanced when used with hypertonic solutions.
• Dextran shows potential benefits in resuscitation with hypertonic saline by reducing microvascular leakage and increasing intravascular volume.