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Cardiovascular Studies during Controlled Baroreflex Activation in the Dog: II. Effects of Metoprolol and Enflurane
Author(s) -
HENRIKSSON B. Å.,
BIBER B.,
LUNDBERG D.,
MARTNER J.,
PONTÉN J.
Publication year - 1985
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1985.tb02166.x
Subject(s) - medicine , baroreceptor , vascular resistance , cardiac output , baroreflex , anesthesia , carotid sinus , cardiac index , stroke volume , cardiology , blood pressure , heart rate , reflex bradycardia , reflex , metoprolol
An experimental model was designed to study circulatory drug effects with or without barostatic reflex influences. In dogs anaesthetized with chloralose, both carotid sinuses were perfused from a femoral by‐pass either with systemic arterial pressure or with a pump in order to control the sinus pressure. Cardiac and aortic baroreceptors were denervated. I. v. metoprolol (240 μg ⋅ kg ‐1 + 102 μg ⋅ kg ‐1 ⋅ h ‐1 ) with constant carotid sinus pressure and thereby constant baroreceptor activation reduced cardiac output, heart rate, cardiac contractility and left ventricular stroke work index. Systemic vascular resistance increased. This response was independent of the degree of baroreflex activation. During the combined administration of enflurane (1.6% end‐tidal concentration) and metoprolol, cardiac performance (cardiac output, stroke volume, heart rate, cardiac contractility and left ventricular stroke work index) was depressed independent of the degree of baroreflex activation. Barostatic reflexes, however, counteracted an observed decrease in systemic vascular resistance. This reflex vascular response was, during metoprolol‐enflurane administration, associated with an increased left ventricular end‐diastolic pressure.