Biochemical factors influencing erythrocyte deformability and capillary entrance phenomena

Evaluation of the effects of biochemical modification of erythrocytes by low pressure filtration through Nuclepore filters of 2.8 and 3.0 micrometer pore diameter and glass micropipettes of 2.7 and 3.0 micrometer internal diameter and channel length greater than 100 micrometer indicates the relative sensitivity of the micropipette in detection of reduction of cellular deformability. In dynamic studies of erythrocyte entrance behaviour on micropipettes, the significance of induced relative sphericity on cellular deformability was evident. Reduction of intracellular ATP, cellular pH, sphere induction by bifunctional membrane protein cross-linking reagents and lead caused diminution in cellular deformability, attributable to the more spherical shape. Similarly echinocyte formation by effects of aged plasma, oleate and senscence, and stomatocyte induction by chlorpromazine caused marked decrease in capillary entry of cells having flow velocities of approximately 100 micrometer/s in contrast inhibitors of the glucose carrier, of calmodulin and manipulated decrease in membrane lipid of bilayer fluidity did not cause detectable change in cellular deformability. These data emphasize the relative importance of erythrocytic shape as a determinant of cellular deformability and suggest that necessity for adequate control of shape change is necessary when examining effects of biochemical manipulations on membrane elasticity and cellular deformability. The preliminary date from capillary entrance experiment indicate the importance of dynamic experiments in in vitro studies of microcirculation.