Baroreflex function in conscious rats submitted to iron overload

Brazilian Journal of Medical and Biological Research

L.m. Cardoso²  M.l. Pedrosa²  M.e. Silva¹  M.f.d. Moraes¹  E. Colombari¹  D.a. Chianca-jr.² 

[1] ,Universidade Federal de Ouro Preto NUPEB Departamento de Ciências Biológicas

关键词: Baroreflex;    Iron overload;    Heart rate;    Blood pressure;    Iron dextran;    Deferoxamine;   

DOI  :  10.1590/S0100-879X2005000200008

来源: SciELO

【 摘 要 】

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.

【 授权许可】

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