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Type: Artigo de periódico
Title: The influence of septal lesions on sodium and water retention induced by Walker 256 tumor
Author: Guimarães, F.
Rettori, O.
Vieira-Matos, A.N.
Fernandes, G.A.
Abstract: In the course of studies on the effects of septal area lesions on neuroimmunomodulation and Walker 256 tumor development, it was observed that tumor-induced sodium and water retention was less marked in lesioned than in non-lesioned rats. In the present study possible mechanisms involved in this phenomenon were investigated. The experiments were performed in septal-lesioned (LW; N = 15) and sham-operated (SW; N = 7) 8-week-old male Wistar rats, which received multifocal simultaneous subcutaneous (sc) inoculations of Walker 256 tumor cells about 30 days after the stereotaxic surgery. Control groups (no tumor, sham-operated food-restricted (SFR), N = 7) and lesioned food-restricted (LFR, N = 10) were subjected to a feeding pattern similar to that observed in tumor-bearing animals. Multifocal inoculation of Walker 256 tumor rapidly induces anorexia, which is paradoxically accompanied by an increase in body weight, as a result of renal Na+ and fluid retention. These effects of the tumor were also seen in LW rats, although the rise in fractional sodium balance during the early clinical period was significantly smaller than in SW rats (day 4: SW = 47.6 ± 6.4% and LW = 13.8 ± 5.2%; day 5: SW = 57.5 ± 3.5% and LW = 25.7 ± 4.8%; day 6: SW = 54.4 ± 3.8% and LW = 32.1 ± 4.4%; P<0.05), suggesting a temporary reduction in tumor-induced sodium retention. In contrast, urine output was significantly reduced in SW rats and increased in LW rats (LW up to -0.85 and SW up to 4.5 ml/100 g body weight), with no change in osmolar excretion. These temporary changes in the tumor's effects on LW rats may reflect a reversal of the secondary central antidiuretic response induced by the tumor (from antidiuretic to diuretic).
Subject: Na+ retention
secondary diuretic response
tumor systemic effects
septal area lesion
multifocal tumor inoculation
Walker 256 tumor
Editor: Associação Brasileira de Divulgação Científica
Rights: aberto
Identifier DOI: 10.1590/S0100-879X1999000300010
Date Issue: 1-Mar-1999
Appears in Collections:Unicamp - Artigos e Outros Documentos

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