Baroreflex function in conscious rats submitted to iron overload

Baroreflex function in conscious rats submitted to iron overload

Author Cardoso, Leonardo Máximo Google Scholar
Pedrosa, Maria Lúcia Silva Google Scholar
Silva, Marcelo Eustáquio Google Scholar
Moraes, Márcio Flávio Dutra Google Scholar
Colombari, Eduardo Autor UNIFESP Google Scholar
Chianca-Junior, Deoclécio Alves Google Scholar
Institution Universidade Federal de Ouro Preto NUPEB Departamento de Ciências Biológicas
Universidade Federal de Ouro Preto Escola de Nutrição Departamento de Alimentos
Universidade Federal de Minas Gerais Instituto de Ciências Biológicas Departamento de Fisiologia e Biofísica
Universidade Federal de São Paulo (UNIFESP)
Abstract Our hypothesis is that iron accumulated in tissue, rather than in serum, may compromise cardiovascular control. Male Fischer 344 rats weighing 180 to 220 g were divided into 2 groups. In the serum iron overload group (SIO, N = 12), 20 mg elemental iron was injected ip daily for 7 days. In the tissue iron overload group (TIO, N = 19), a smaller amount of elemental iron was injected (10 mg, daily) for 5 days followed by a resting period of 7 days. Reflex heart rate responses were elicited by iv injections of either phenylephrine (0.5 to 5.0 µg/kg) or sodium nitroprusside (1.0 to 10.0 µg/kg). Baroreflex curves were determined and fitted to sigmoidal equations and the baroreflex gain coefficient was evaluated. To evaluate the role of other than a direct effect of iron on tissue, acute treatment with the iron chelator deferoxamine (20 mg/kg, iv) was performed on the TIO group and the baroreflex was re-evaluated. At the end of the experiments, evaluation of iron levels in serum confirmed a pronounced overload for the SIO group (30-fold), in contrast to the TIO group (2-fold). Tissue levels of iron, however, were higher in the TIO group. The SIO protocol did not produce significant alterations in the baroreflex curve response, while the TIO protocol produced a nearly 2-fold increase in baroreflex gain (-4.34 ± 0.74 and -7.93 ± 1.08 bpm/mmHg, respectively). The TIO protocol animals treated with deferoxamine returned to sham levels of baroreflex gain (-3.7 ± 0.3 sham vs -3.6 ± 0.2 bpm/mmHg) 30 min after the injection. Our results indicate an effect of tissue iron overload on the enhancement of baroreflex sensitivity.
Keywords Baroreflex
Iron overload
Heart rate
Blood pressure
Iron dextran
Language English
Date 2005-02-01
Published in Brazilian Journal of Medical and Biological Research. Associação Brasileira de Divulgação Científica, v. 38, n. 2, p. 205-214, 2005.
ISSN 0100-879X (Sherpa/Romeo, impact factor)
Publisher Associação Brasileira de Divulgação Científica
Extent 205-214
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000227480900008
SciELO ID S0100-879X2005000200008 (statistics in SciELO)

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