Plasma glucose concentrations and the development of blood emboli and hemolysis

Plasma glucose concentrations were measured in heparinized dog blood as the blood was sheared in polycarbonate coni-cylindrical test cells. The glucose depletion rate during the 4 hr tests increased with increasing shear rate (480 to 2100 sec-1) but was independent of the surface/volume ratio (7.0 and 12.7 cm-1). These results suggest that the glucose metabolism in red cells (the dominant consumer of blood glucose) increases more from shear-induced stretching or tearing of red cells that adhere to the wall than from cell-boundary collisions. (Changes in platelet and leukocyte glucose metabolism would not have been detected in our measurements of whole blood glucose concentrations.) The rate of glucose depletion was also independent of the extent and rate of hemolysis and the extent of microemboli formation (as measured by SFP). When insulin-induced hypoglycemic blood was used to fill the test cells, the resulting hemolysis and SFPs were not significantly different from hemolysis and SFPs produced in normoglycemic blood from the same donors. Thus red cells (which have negligible glycogen stores) do not depend significantly on plasma glucose to resist hemolysis, and platelets may rely on their substantial glycogen storage to form microemboli during hypoglycemia.