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Am J Hypertens. 2004 Oct;17(10):947-54.

Treatment by n-acetylcysteine and melatonin increases cardiac baroreflex and improves antioxidant reserve.

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1
Research Group on Autonomic Nervous System, Department of Physiology, Faculty of Medicine, University of Montréal, Montréal, Québec, Canada.

Abstract

BACKGROUND:

The aims of this study were to investigate the effects of melatonin and n-acetylcysteine on the baroreflex sensitivity and to verify whether those effects were correlated with their antioxidant capacity in Wistar-Kyoto and spontaneously hypertensive rats (SHR).

METHODS:

Rats were treated with 30 mg/kg/day of melatonin or 4 g/kg/day of n-acetylcysteine for 4 weeks. Changes in mean arterial pressure, heart rate, plasma norepinephrine, and epinephrine were measured in conscious rats after an intravenous injection of phenylephrine or sodium nitroprusside.

RESULTS:

The SHR were characterized by decreased reflex chronotropic responses to phenylephrine and sodium nitroprusside (P < .001 and P < .001), as well as by an enhanced increase in plasma catecholamine concentrations in response to sodium nitroprusside (P < .001). Melatonin and n-acetylcysteine produced a significant reduction in mean arterial pressure and heart rate in SHR (P < .001). Melatonin and n-acetylcysteine improved bradycardic (P < .001) and tachycardic (P < .001) baroreflex responses in SHR without modifying catecholamine responses. The antioxidant reserve, which was reduced in SHR as reflected by the lower glutathione peroxidase activity in plasma (P < .05), was normalized by n-acetylcysteine and melatonin (P < .05). n-acetylcysteine (P < .001) and melatonin (P < .05) increased glutathione peroxidase activity in erythrocytes from SHR.

CONCLUSIONS:

The results of the present study suggest that melatonin and n-acetylcysteine improve the baroreflex response in SHR in correlation with the antioxidant effects of these substances.

PMID:
15485759
DOI:
10.1016/j.amjhyper.2004.06.009
[Indexed for MEDLINE]
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