Effect of stress on erythrocyte deformability, influence of gender and menstrual cycle.

This study aimed to investigate the effect of acute mental stress on erythrocyte deformability (ED) in women during different phases of the menstrual cycle and to compare the results with men. For this purpose, healthy males (n=10) and females (n=10) (during follicular and luteal phases) underwent Stroop color-word interference and cold pressor tests. Hemoglobin, hematocrit and leukocyte counts before and after this stress test revealed no difference in either group; erythrocyte sedimentation rate was significantly lower in the post-test samples in all. In all groups erythrocyte filtration time was significantly higher and thus ED was significantly lower after the stress test (mean+/-SEM, PRE-TEST: follicular: 3.08+/-0.05; luteal: 2.07+/-0.05; men: 2.9+/-0.05) (POST-TEST: follicular: 4.5+/-0.07; luteal: 4.1+/-0.07; men: 4.39+/-0.1). ED was appreciably influenced by gender and menstrual cycle. Women at the luteal phase had better ED compared to both women at the follicular phase and men, the effect being especially pronounced in the pre-test samples. Our results suggest that stress may induce cardiovascular diseases by lowering ED in both genders. The effect of stress on ED varies with gender and during different phases of the menstrual cycle, which may be explained by variations in the sex hormones.

Changes in blood haemorheological parameters after submaximal exercise in trained and untrained subjects.

The blood stream is affected by viscosity and many other haemorheological factors such as lipid peroxidation in the plasma and red blood cells. The aim of this study was to investigate the changes of haemorheological parameters after submaximal exercise in trained and untrained subjects. The results indicated that heart rate, lymphocyte count, erythrocyte deformability, plasma lipid peroxide levels and erythrocyte glutathione peroxidase activity are increased after submaximal exercise.

Effect of erythrocyte deformability on renal hemodynamics and plasma renin activity.

Increased blood viscosity has been previously noted in a subgroup of patients with essential hypertension with concomitant high plasma renin activity (PRA). It has been suggested that the cause of hyperviscosity in hypertensives is the presence of circulating red blood cells (RBCs) that were rendered less deformable by significant alterations in their cationic milieu, namely an increase in intracellular concentration of calcium and sodium. The relation between RBC deformability and PRA however is not clear. Our study was conducted to examine this issue. RBC deformability was reduced experimentally, and its effects on renal blood flow, renal artery resistance, glomerular filtration rate and PRA were investigated in experimental (n = 8) and control (n = 4) groups of dogs. Blood was collected from the animals before the experiments and incubated with 0.025% glutaraldehyde. These hardened RBCs were administered to the animals through exchange transfusions. Following the exchange transfusion with the hardened RBCs, there were no changes in renal blood flow, renal artery resistance, and the creatinine clearance. The only change observed was an increase in PRA. In the control group, all parameters that were determined remained unchanged. The data are consistent with the notion that the presence of circulating hardened RBCs may by itself increase PRA, and this effect can be important in some types of hypertension and some other disorders in which impaired deformability of RBCs have been reported.

Hematological and hemorheological effects of air pollution.

Selected hematological parameters and erythrocyte deformability indexes for 16 young male military students were compared before and after a period of exposure to heavy pollution. These students lived in Ankara, which has a serious air pollution problem. The mean sulfur dioxide levels measured at a station proximal to the campus where the students lived were 188 micrograms/m3 and 201 micrograms/m3 during first and second measurements, respectively. During the period between the two measurements, the mean sulfur dioxide level was 292 micrograms/m3. Significant erythropoiesis was indicated by increased erythrocyte counts and hemoglobin and hematocrit levels. Methemoglobin percentage was increased to 2.37 +/- 0.49% (mean +/- standard error) from 0.51 +/- 0.23%. Sulfhemoglobinemia was present in six subjects after the period of pollution, but it was not present in any student prior to this period. Significant increases in erythrocyte deformability indexes were observed after the period of pollution, i.e., from 1.13 +/- 0.01 to 1.21 +/0 0.02, implying that erythrocytes were less flexible, which might impair tissue perfusion.

In vitro effects of thyroxine on the mechanical properties of erythrocytes.

In vitro effects of thyroxine on erythrocyte deformability and mechanical fragility were observed. Deformability of erythrocytes was improved in a dose dependent manner by thyroxine. Mechanical hemolysis was found to be lower if thyroxine was included in erythrocyte suspensions at concentrations close to the physiological levels (10(-9)M). These changes might be related to the alterations of intracellular calcium concentration, as in the erythrocyte suspensions containing 10(-9)M thyroxine, intracellular calcium concentration was found to be 30 times lower than the control suspensions which did not contain thyroxine. Thyroxine also reduced the mechanical hemolysis ratio in calcium loaded cells. These observations suggest that thyroxine might play some role in the regulation of the mechanical properties of erythrocytes which might be mediated via the effects on calcium metabolism.