Efeito do tratamento multiprofissional sobre a relação da estabilidade de membrana de eritrócitos com variáveis sanguíneas em adolescentes obesos

Abstract

The intake of energy excess and sedentary lifestyle are conditions associated with the development of obesity and resistance to insulin action. The origin of this resistance is tentatively explained by several theories, which include the theory of membrane resistance, whereby an excessive content of cholesterol would be a determinant of changes in the behavior of this cellular barrier, particularly in the transduction of hormonal signals. These changes in the membrane behavior would result from the excess supply of cholesterol and would occur in all cells of the human organism, with the greatest impact on myocytes, which are responsible for a significant consumption of glucose from the blood. The composition and behavior of the erythrocyte membrane is also influenced blood levels of cholesterol and glucose, such that these cells constitute a minimally invasive model to study the behavior of membranes in situations of energy homeostasis break, as occurs in obesity. The osmotic stability of the erythrocyte represents a representative property of the behavior of the cell membrane. It can be conveniently studied by analyzing the sigmoidal curve of the dependence of light absorbance of hemoglobin released in the lysis produced by a hypotonicity gradient. This curve can be adjusted to the Boltzmann equation, with determination of the salt concentration in the point of half transition (H50) and the variation in the concentration of salt required to promote the lysis transition (dX). The variables H50 and dX present inverse and direct relationships, respectively, with the osmotic stability of erythrocytes. The reason dX/H50 is a combined variable that presents a direct relation with the stability of erythrocyte membrane. In this study, the stability of erythrocytes was assessed before and after an activity program that included nutritional and psychological counseling, as well as four weekly sessions of aerobic and resistance exercises, lasting 30 minutes each session, for five months, in a population consisting of 44 adolescents (16 males and 28 females). To understand the interrelationships of the behavior of erythrocytes with variables subject to change during the training program established, were also evaluated anthropometric, hematological, biochemical, hormonal, and some biomarkers of organs and tissues integrity. The study ended with 21 adolescents (8 males and 13 females). At the end of the program of training, there was a decrease in all anthropometric variables considered (body mass, body mass index, waist circumference and fat content); an increase of some of the hematological variables [hemoglobin (Hb), hematocrit (Ht), mean corpuscular volume (MCV) and distribution width of red blood cells (RDW)]; a reduction in blood lipids (total cholesterol, VLDL-C and triglycerides); elevation in the blood levels of creatinine and sodium and decrease in the potassium levels; elevation in the blood concentrations of total and direct bilirubin and decreased activity of γ-glutamyl transferase (γGT); decreased levels of thyroid stimulating hormone (TSH) and elevated levels of free thyroxine (FT4) and follicle- stimulating hormone (FSH); and increased stability of erythrocytes. A cross-sectional treatment of the correlations between the variables of stability and each of the variables analyzed in the study showed that: 1) the values of H50 increased with increase in hemoglobin, mean corpuscular hemoglobin (MCH), mean corpuscular volume (MCV), sodium and luteinizing hormone (LH) and decreased with increasing levels of glycated hemoglobin (Hb1C); 2) the values of dX decreased with increase in RBC, Hb, MCH, MCHC, VLDL-C, Tg, urea, creatinine, potassium and cortisol, and increased with increase in RDW; 3) the values of dX/H50 maintained the same pattern of dX correlations, except for urea and creatinine levels. These results suggest that the increased stability of erythrocytes after the training program was driven by an increase in RDW, since this was the only parameter that showed a direct relationship with dX/H50, and perhaps by decreasing levels of Hb1C, which was the only parameter that showed an inverse relationship with H50, although the decline in Hb1C after the training program was not statistically significant.