Chronic infusion of angiotensin II resets baroreflex control of heart rate by an arterial pressure-independent mechanism

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Abstract

The purpose of this study was to test the hypothesis that chronic infusion of angiotensin II (Ang II) in rabbits resets the cardiac baroreflex to a higher arterial pressure level by a pressure-independent mechanism. This hypothesis was tested by determining whether the resetting would be reversed soon after the Ang II infusion was stopped even if the hypertension was maintained by infusion of another vasoconstrictor. Relationships between arterial pressure and heart rate were determined by infusion of increasing closes of nitroprusside to decrease pressure and increase heart rate, followed by increasing doses of phenylephrine to increase pressure and decrease heart rate. After 9 to 10 days of Ang II infusion (20 ng · kg-1 · min-1) arterial pressure was increased from 62±2 to 94±3 mm Hg (P-1 · min-1), and 30 minutes later arterial pressure decreased slightly (P-1 · min-1). These data indicate that angiotensin-induced chronic baroreflex resetting is partially reversed soon after Ang II infusion is stopped, despite maintenance of the hypertensive state, and suggest that long-term increases in angiotensin reset the cardiac baroreflex in part by an arterial pressure-independent mechanism.

Original languageEnglish (US)
Pages (from-to)420-424
Number of pages5
JournalHypertension
Volume26
Issue number3
StatePublished - 1995

Fingerprint

Baroreflex
Angiotensin II
Arterial Pressure
Heart Rate
Angiotensins
Pressure
Nitroprusside
Phenylephrine
Vasoconstrictor Agents
Maintenance
Rabbits
Hypertension

Keywords

  • blood pressure
  • heart rate
  • hypertension, essential
  • methoxamine
  • nitroprusside
  • phenylephrine
  • rabbits
  • sympathetic nervous system

ASJC Scopus subject areas

  • Internal Medicine

Cite this

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abstract = "The purpose of this study was to test the hypothesis that chronic infusion of angiotensin II (Ang II) in rabbits resets the cardiac baroreflex to a higher arterial pressure level by a pressure-independent mechanism. This hypothesis was tested by determining whether the resetting would be reversed soon after the Ang II infusion was stopped even if the hypertension was maintained by infusion of another vasoconstrictor. Relationships between arterial pressure and heart rate were determined by infusion of increasing closes of nitroprusside to decrease pressure and increase heart rate, followed by increasing doses of phenylephrine to increase pressure and decrease heart rate. After 9 to 10 days of Ang II infusion (20 ng · kg-1 · min-1) arterial pressure was increased from 62±2 to 94±3 mm Hg (P-1 · min-1), and 30 minutes later arterial pressure decreased slightly (P-1 · min-1). These data indicate that angiotensin-induced chronic baroreflex resetting is partially reversed soon after Ang II infusion is stopped, despite maintenance of the hypertensive state, and suggest that long-term increases in angiotensin reset the cardiac baroreflex in part by an arterial pressure-independent mechanism.",
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KW - blood pressure

KW - heart rate

KW - hypertension, essential

KW - methoxamine

KW - nitroprusside

KW - phenylephrine

KW - rabbits

KW - sympathetic nervous system

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