Inverse relationship between heart rate and blood pressure variabilities in rats

Alberto U. Ferrari, Anna Daffonchio, Francesco Albergati, Giuseppe Mancia

Research output: Contribution to journalArticle

Abstract

The interplay of heart rate variability, baroreceptor control of heart rate, and blood pressure (BP) variability was examined in chronically instrumented, unanesthetized, freely moving rats in which the efferent neural influences on heart rate were pharmacologically altered. In each rat, BP was recorded continuously for 90 minutes in the control condition and in one or more of the following conditions: 1) β-adrenergic receptor blockade by propranolol, 1 mg/kg; 2) cholinergic blockade by atropine, 0.75 mg/kg, and 3) combined blockade by propranolol plus atropine. Each BP recording was analyzed beat- to-beat by a computer that calculated heart rate and BP variabilities, both expressed as variation coefficients. In addition, under each condition the sensitivity of the arterial baroreceptor control of heart rate was assessed by measuring the reflex changes in pulse interval in response to BP changes induced by bolus i.v. injections of phenylephrine and nitroprusside. As compared with the control condition, 1) propranolol (n = 10) reduced heart rate variability by 23 ± 4% (p < 0.01), only slightly impaired baroreceptor reflex sensitivity, and did not significantly modify BP variability (+11 ± 7%); 2) atropine (n = 11) reduced heart rate variability by 30 ± 7% (p < 0.01), drastically impaired baroreceptor reflex sensitivity, and increased BP variability (+ 40 ± 8%, p < 0.01); 3) combined blockade (n= 10) caused variability and baroreceptor reflex changes similar to those induced by atropine alone. Thus, heart rate variability depends on both vagal and sympathetic influences. However, only the former component affects BP variability, that is, it plays an antioscillatory role. This role is likely to originate from arterial baroreceptor modulation of vagal cardiac drive.

Original languageEnglish
Pages (from-to)533-537
Number of pages5
JournalHypertension
Volume10
Issue number5
Publication statusPublished - 1987

Keywords

  • Arterial baroreceptors
  • Blood pressure variability
  • Cardiac parasympathetic nervous system
  • Cardiac sympathetic nervous system
  • Rats

ASJC Scopus subject areas

  • Internal Medicine

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    Ferrari, A. U., Daffonchio, A., Albergati, F., & Mancia, G. (1987). Inverse relationship between heart rate and blood pressure variabilities in rats. Hypertension, 10(5), 533-537.