Studies on sequestration of neuraminidase-treated red blood cells

The effects of reduction in the surface charge of red blood cells (RBCs) on regional blood flow and RBC distribution were studied in rats anesthetized with pentobarbital sodium. RBCs were treated with neuraminidase to reduce their electrophoretic mobility by 56%. Normal and neuraminidase-treated RBCs labeled with 51Cr or 111In were injected into a femoral vein while an equal volume of blood was simultaneously withdrawn from a femoral artery. More than 70% of the neuraminidase-treated RBCs injected disappeared from the circulating blood in 30 min compared with less than 2% of normal RBCs. The relative distributions of neuraminidase-treated RBCs to normal RBCs, as determined from radioactivity counting, were significantly greater than 1 in the spleen (5.65 +/- 0.97, mean +/- SD), the liver (2.84 +/- 0.21), the lung (1.48 +/- 0.31), and the kidney (1.49 +/- 0.27), indicating a preferential trapping of neuraminidase-treated RBCs in these regions. This ratio was approximately 1 in all other organs. Regional blood flows in tissues were determined with 15-micron microspheres in the control period and after the infusion of neuraminidase-treated RBCs (experimental). Experimental-to-control blood flow ratios were 0.40 +/- 0.05 in the spleen, 0.66 +/- 0.06 in the liver, 0.78 +/- 0.03 in the lung, and 0.78 +/- 0.09 in the kidneys; this ratio was approximately 1 in all other organs. An experimental-to-control blood flow ratio less than 1 indicates a reduction in blood flow; this occurred in the same organs as those with trapping of neuraminidase-treated RBCs