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Superoxide scavenging in the rostral ventrolateral medulla blunts the pressor response elicited by peripheral chemoreflex activation in conscious rats
Author(s) -
Ribeiro Thaís Porto,
Socorro FrançaSilva Maria,
PortoSilva Clarice,
Medeiros Isac Almeida,
Braga Valdir A
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.lb689
Subject(s) - rostral ventrolateral medulla , chemistry , superoxide , microinjection , medicine , endocrinology , losartan , angiotensin ii , superoxide dismutase , reactive oxygen species , medulla oblongata , oxidative stress , receptor , central nervous system , biochemistry , enzyme
Reactive oxygen species have been implicated in sleep obstructive apnea and hypertension. However, a link between oxidative stress and peripheral chemoreflex (PC) integration within the RVLM has never been investigated. Here, we tested the hypothesis that the pressor response induced by PC activation involves the angiotensin‐II/AT 1 R/superoxide pathway within the rostral ventrolateral medulla (RVLM). Seventeen male Wistar rats (260–300g) were implanted with bilateral guide‐canulae towards the RVLM four days prior the experiments. PC activation with potassium cyanide (80 μg/Kg, i.v.) produced a increase in blood pressure, which was attenuated 2 minutes after bilateral microinjection of Losartan (1 μM/50 nL), an AT 1 receptor antagonist, in the RVLM (+54±4 vs +19±3 ΔmmHg P<0.05, n=6). Moreover, superoxide scavenging in the RVLM using a superoxide dismutase (SOD) mimetic, Tempol (50 nmol/50 nL), significantly blunted the pressor response to PC activation (+50±3 vs +18±3 ΔmmHg P<0.05, n=7), while saline did not (n=4). Taken together, these data suggest that the neurotransmission of the PC within the RVLM involves, at least in part, the activation of AT 1 receptors and downstream superoxide formation.