Abstract
Objective: To determine superfusate-induced changes in the distribution of plasma proteins in the perimicrovascular interstitial matrix.
Methods: Rats were anesthetized with sodium pentobarbital and a mesenteric loop was exteriorized. Intravital video microspectrophotometry was performed using wavelengths of 280, 320, and 700 nm. The images were analyzed to give protein and collagen spatial distributions in vascular regions of rat mesenteric tissue. Perimicrovascular protein concentrations were fitted to an exponential decay model ci + cv exp (-x/k), where ci is distal protein concentration, ci + cv is the protein concentration proximal to the vessel, x is the distance from the vessel wall, and k is the decay constant indicating protein gradient slope.
Results: Before superfusion with 0.5-ml normal saline, ci = 1.45 ± 0.13 g/dl, ci + cv = 4.56 ± 0.23 g/dl. After the first superfusion, ci decreased (p < 0.01) to 0.53 ± 0.06 g/dl; following a second superfusion, ci decreased to 0.4 ± 0.03 g/dl; an additional final superfusion caused a further decrease to 0.33 ± 0.02 g/dl. ci + cv also decreased significantly during repeated superfusions to 2.92 ± 0.15, 2.35 ± 0.25, and 2.1 ± 0.12 g/dl, respectively.
Conclusions: Superfusion produced changes in perivascular and distal interstitial matrix protein distribution. Protein concentration proximal to the microvessel remained higher than distal concentrations. This could be due to increased gel concentrations inhibiting protein mobility.