PressÃo arterial, frequÃncia cardÃaca e sua modulaÃÃo autonÃmica em ratos malnutridos em diferentes idades

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Undernutrition during human development is one of the principal causes of various systemic alterations and is characterized as one of the greatest public health problems in underdeveloped countries. Using an experimental model that reproduces in rats a type of human malnutrition found in the Northeast of Brazil, we use a multideficient hypoproteic and hypercaloric diet developed by the Nutrition Department of the UFPE (Federal University of Pernambuco). The objective of this study was to investigate the effects of this diet on some cardiovascular parameters, that is, on the levels of Systole Blood Pressure (SBP), on Heart Rate (HR), and its autonomic modulation, evaluated through spectral analysis in non-anesthetized Wistar rats from weaning to nine months of age. Morphological and histological studies of the heart were also undertaken. The animals were separated into two experimental groups: one Control Group (CG) with rats fed the Labina diet, and one Malnourished Group (MG), submitted to the multideficient diet. From the third month of life up to the age of nine months, the rats from both groups were submitted on a weekly basis to an evaluation of body weight, record of SBP (indirectly, via plethysmography of the caudal artery) and of the ECG (by a non-invasive method developed in our Laboratory). From the HR signal, obtained by the ECG, spectral analysis of the HR was performed through the autoregressive method for the purpose of determining the degree of cardiac autonomic modulation. Beginning in the third month of life, eight rats were selected from each group, with ages of three, five, seven and nine months, with three animals for the morphological study and five for the histological study. Statistical analysis was undertaken through one-way ANOVA, Tukey post hoc test and of the unpaired Studentâs t-test (p<0.05). The results showed that the MG in relation to the CG presented: significantly less body weight (p<0.001), at all ages; greater HR (p<0.05) at the ages of three, four and five months, and lower from the sixth to the ninth month; SBP without significant differences between the groups, for each age, however with a reduction in the proportion that the rat from the MG grew older; spectral analysis with significant increase of the LF components from the third month on (p<0.05), giving evidence of sympathetic predominance; and greater autonomic cardiac balance showing that, although aging influences the autonomic behavior of the heart, it may also be altered by nutrition. Morphologically, an increase in the ventricle weight/body weight ratio was found in the MG and, in the histology of the ventricles, the presence of apoptosis, necrosis, inflammatory cells and altered healing processes. Together, these results show that the heart of the MG was not spared from malnutrition and that the histophysiological findings draw near to the clinical signs found in patients with advanced Congestive Heart Failure. Thus, this model of malnutrition presents itself as an important tool that may be used to elucidate the molecular mechanisms involved in this syndrome

ASSUNTO(S)

chronic malnutrition modulaÃÃo autonÃmica da frequÃncia cardÃaca biologia e fisiologia dos microorganismos malnutriÃÃo crÃnica pressÃo arterial blood pressure autonomic modulation of heart rate

ACESSO AO ARTIGO

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