Stimulation by bradykinin of afferent vagal C-fibers with chemosensitive endings in the heart and aorta of the dog

Marc P Kaufman, D. G. Baker, H. M. Coleridge, J. C G Coleridge

Research output: Contribution to journalArticle

84 Citations (Scopus)

Abstract

Bradykinin applied directly to the epicardium evokes a reflex increase in blood pressure by stimulating sympathetic afferent nerve endings in the heart, but injected into the coronary artery it evokes vagally mediated reflex decreases in heart rate and blood pressure. The afferents initiating these latter depressor effects have not been identified. We have attempted to determine which vagal sensory nerve endings in the heart are stimulated by bradykinin. In anesthetized dogs, we recorded impulses from afferent vagel fibers with endings in the heart and aorta and injected bradykinin (0.3-1.0) μg/kg) into the left atrium. Neither A- nor C-fiber mechanoreceptors nor aortic body chemoreceptors were stimulated directly by bradykinin, any changes in firing of atrial or ventricular mechanoreceptors, or of aortic baroreceptors or chemoreceptors, being secondary to the cardiovascular effects of bradykinin. However, 16 of 20 irregularly discharging vagal C-fibers with chemosensitive endings in the left ventricle, left atrium, and aorta were stimulated by bradykinin; firing increased from 0.2 ± 0.1 to 7.8 ± 1.4 (mean ± SE) impulses/sec and usually remained above control for about 30 seconds. These chemosensitive endings were not stimulated by ventilating the lungs with 5% O 2 in N 2, but they were stimulated by injecting capsaicin or phenyl diguanide into the left atrium. Four chemosensitive endings in the ventricular epicardium were also stimulated by dripping bradykinin (1 μg/ml) onto the heart. We suggest that these chemosensitive vagal C-fibers are responsible for the reflex decreases in heart rate and blood pressure elicited by bradykinin.

Original languageEnglish (US)
Pages (from-to)476-484
Number of pages9
JournalCirculation Research
Volume46
Issue number4
StatePublished - 1980
Externally publishedYes

Fingerprint

Unmyelinated Nerve Fibers
Bradykinin
Aorta
Dogs
Heart Atria
Reflex
Mechanoreceptors
Pericardium
Blood Pressure
Aortic Bodies
Heart Rate
Pressoreceptors
Nerve Endings
Capsaicin
Sensory Receptor Cells
Heart Ventricles
Coronary Vessels
Lung

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

Cite this

Stimulation by bradykinin of afferent vagal C-fibers with chemosensitive endings in the heart and aorta of the dog. / Kaufman, Marc P; Baker, D. G.; Coleridge, H. M.; Coleridge, J. C G.

In: Circulation Research, Vol. 46, No. 4, 1980, p. 476-484.

Research output: Contribution to journalArticle

Kaufman, Marc P ; Baker, D. G. ; Coleridge, H. M. ; Coleridge, J. C G. / Stimulation by bradykinin of afferent vagal C-fibers with chemosensitive endings in the heart and aorta of the dog. In: Circulation Research. 1980 ; Vol. 46, No. 4. pp. 476-484.
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