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Age‐related decreases in baroreflex sensitivity and circadian variation of blood pressure and heart rate are mediated by centrally produced hydrogen peroxide
Author(s) -
Erdos Benedek,
Frimpong Hanns,
Whidden Melissa,
Kirichenko Nataliya,
Tumer Nihal
Publication year - 2011
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.25.1_supplement.645.15
Recent studies indicate that hydrogen peroxide (H2O2) has a significant role in central regulation of sympathetic nerve activity (SNA) and blood pressure (BP). We have found previously that catalase expression decreases significantly in the hypothalamus and brain stem with age. Therefore, we investigated whether H2O2 is involved in age‐related dysregulation of SNA and BP. Circadian variation of BP and heart rate (HR), and baroreflex regulation of heart rate (HR) and lumbar SNA (LSNA) were analyzed using radiotelemetry in young (5 mo) and old (24 mo) F344 × BN rats. Aminotriazole (ATZ ‐ 5nmol/h), an inhibitor of catalase or CSF was infused icv for 2 wks using osmotic minipumps. Resting daytime BP was significantly higher in old vs young rats (106.4±1.2 vs 96.6±1.6 mmHg), while amplitude of circadian BP and HR variation was reduced by 40% in old rats. ATZ infusion significantly reduced circadian variation of BP and HR in young rats, but had no effect in old. Baroreflex sensitivity (BRS) of HR and LSNA were also markedly reduced in old rats vs young by 50% and 60%, respectively as tested with iv infusions of phenylephrine and sodium nitroprusside. ATZ treatment blunted BRS of HR and LSNA in both age groups, however, this effect was much more pronounced in young rats. As a result, BRS of HR and LSNA in young ATZ‐treated rats became similar to those observed in old rats. These results indicate that reduced central catalase activity and elevated H2O2 levels may play a significant role in age‐related dysregulation of SNA and BP.