Influence of acute exercise on the osmotic stability of the human erythrocyte membrane.

This study evaluated the effects of 2 different types of acute aerobic exercise on the osmotic stability of human erythrocyte membrane and on different hematological and biochemical variables that are associated with this membrane property. The study population consisted of 20 healthy and active men. Participants performed single sessions of 2 types of exercise. The first session consisted of 60 min of moderate-intensity continuous exercise (MICE). The second session, executed a week later, consisted of high-intensity interval exercise (HIIE) until exhaustion. The osmotic stability of the erythrocyte membrane was represented by the inverse of the salt concentration (1/H50) at the midpoint of the sigmoidal curve of dependence between the absorbance of hemoglobin and the NaCl concentration. The values of 1/H50 changed from 2.29±0.1 to 2.33±0.09 after MICE and from 2.30±0.08 to 2.23±0.12 after HIIE. During MICE mean corpuscular volume increased, probably due to in vivo lysis of older erythrocytes, with preservation of cells that were larger and more resistant to in vitro lysis. The study showed that a single bout of acute exercise affected erythrocyte stability, which increased after MICE and decreased after HIIE.

Bivariate and multivariate analyses of the correlations between stability of the erythrocyte membrane, serum lipids and hematological variables.

The observation that the fluidity must remain within a critical interval, outside which the stability and functionality of the cell tends to decrease, shows that stability, fluidity and function are related and that the measure of erythrocyte stability allows inferences about the fluidity or functionality of these cells. This study determined the biochemical and hematological variables that are directly or indirectly related to erythrocyte stability in a population of 71 volunteers. Data were evaluated by bivariate and multivariate analysis. The erythrocyte stability showed a greater association with hematological variables than the biochemical variables. The RDW stands out for its strong correlation with the stability of erythrocyte membrane, without being heavily influenced by other factors. Regarding the biochemical variables, the erythrocyte stability was more sensitive to LDL-C. Erythrocyte stability was significantly associated with RDW and LDL-C. Thus, the level of LDL-C is a consistent link between stability and functionality, suggesting that a measure of stability could be more one indirect parameter for assessing the risk of degenerative processes associated with high levels of LDL-C.

Evolution of nutritional, hematologic and biochemical changes in obese women during 8 weeks after Roux-en-Y gastric bypasss.

Obesity is a chronic disease of multifactorial origin and currently is a serious public health problem. The treatment of morbid obesity can be effectively done by bariatric surgery. The present study aimed to evaluate the influence of changes in food intake on body composition and some hematologic and biochemical variables in the period of eight weeks after Roux-en-Y gastric bypass (RYGB). The study included 22 women submitted to RYGB. We evaluated anthropometric, nutritional, hematologic and biochemical variables before and 14, 28, 42 and 56 days after surgery. The patients showed a decrease in caloric intake and hence macro- and micronutrients, with significant loss of weight and decrease in body mass index (BMI). Decreases in body weight and BMI were associated with reduced blood levels of total cholesterol, VLDL-C, LDL-C, triglycerides and glucose with time after surgery. The decrease in caloric intake was also associated with decreased intake of protein, iron and calcium, with a decline in hemoglobin, hematocrit and red blood count, and RDW increased after surgery.

Effects of glycerol and sorbitol on the thermal dependence of the lysis of human erythrocytes by ethanol.

In this work, the effects of 1 mol/L glycerol or sorbitol on the thermal dependence (27-47 degrees C) of the lysis of human erythrocytes by ethanol in saline solution (0.154 mol/L NaCl) have been evaluated. Lysis was monitored by measurement of the absorbance at 540 nm. Ethanol produced either lysis or protection against lysis depending on the conditions. These antagonistic effects are attributed to the existence of expanded (R) and compacted (T) erythrocytes, present under conditions of low and high osmolarity, respectively. The transitions of lysis of the R state and formation and lysis of the T state were all found to be sigmoidally defined. The ethanol concentration at the midpoint of the lysis transition of the R state (D(50R)) was found to decrease with increasing temperature and osmolarity. In the presence of glycerol or sorbitol, an increase in temperature led to smaller decreases in D(50R) and osmotic protection against lysis. The ethanol concentration at the midpoint of formation (S(50T)) and lysis (D(50T)) of the T state also decreased with increasing temperature and osmolarity. Lysis of R state erythrocytes is determined by the chaotropic action of ethanol, but the formation and lysis of T state erythrocytes are determined by osmotic pressure effects.