CHANGES IN RAT MESENTERY INTERSTITIAL MATRIX DUE TO SUPERFUSATE

Animal preparations for microscopy often require a superfusate solutio n to cover surgically exposed tissue. There are few, if any, data conc erning the effects of this solution on extravascular protein concentra tion and hydration. The effect of superfusion on mesenteric tissue in anesthetized male Sprague-Dawley rats was studied. Tissue samples were taken from nonsuperfused and superfused tissue and analyzed for hydra tion, albumin, and transferrin content. The mesenteric tissue intersti tial matrix was rapidly altered by normal saline superfusate. After su perfusion, there was a decrease (P < 0.01) in tissue albumin concentra tion from 1.17 +/- 0.27 to 0.10 +/- 0.08 g/dl (n = 9). Tissue hydratio n increased from 4.98 +/- 0.8 mug water/mug dry wt in controls to 7.38 +/- 1.2 mug water/mug dry wt after superfusion. When a range of super fusate albumin concentrations was used (0, 1, 2, and 3 g/dl), tissue a lbumin concentration changed 0.59 +/- 0.09 g/dl for each gram per deci liter change in superfusate concentration (P < 0.0001). The large chan ges in interstitial matrix protein content and hydration suggest that superfusate solution effects need to be considered in microvascular pr otein transport experiments.