Red blood cell (RBC) mechanical properties were investigated after swimming exercise in trained and untrained rats. A group of rats was trained for 6 wk (60 min swimming, daily), and another group was kept sedentary. Blood samples were obtained either within 5 min or 24 h after 60 min swimming in both groups. In the untrained rats, the RBC aggregation index decreased to 2.60 ± 0.4 immediately after exercise from a control value of 6.73 ± 0.18 ( P < 0.01), whereas it increased to 13.13 ± 0.66 after 24 h ( P < 0.01). RBC transit time through 5-μm pores increased to 3.53 ± 0.16 ms within 5 min after the exercise from a control value of 2.19 ± 0.07 ms ( P < 0.005). A very significant enhancement (166%) in RBC lipid peroxidation was detected only after 24 h. In the trained group, the alterations in all these parameters were attenuated; there was a slight, transient impairment in RBC deformability (transit time = 2.64 ± 0.13 ms), and lipid peroxidation was found to be unchanged. These findings suggest that training can significantly limit the hemorheological alterations related to a given bout of exercise. Whether this effect is secondary to the training-induced reduction in the degree of metabolic and/or hormonal perturbation remains to be determined.
Sialic acids rather than glycosaminoglycans affect normal and sickle red blood cell rheology by binding to four major sites on fibrinogen
