Afferent discharges from coronary arterial and ventricular receptors in anaesthetized dogs
1. Previous work has shown that increases in aortic root pressure result in reflex vasodilation, and that this response is likely to result mainly from stimulation of receptors in the coronary arteries, although contribution from left ventricular receptors was not excluded. This investigation was un...
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Published in | The Journal of physiology Vol. 472; no. 1; pp. 785 - 799 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Oxford
The Physiological Society
01.12.1993
Blackwell |
Subjects | |
Online Access | Get full text |
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Summary: | 1. Previous work has shown that increases in aortic root pressure result in reflex vasodilation, and that this response is
likely to result mainly from stimulation of receptors in the coronary arteries, although contribution from left ventricular
receptors was not excluded. This investigation was undertaken to resolve this question and to determine the afferent nerve
fibres likely to be involved in this reflex. 2. In chloralose-anaesthetized dogs a perfusion circuit was used which allowed
us to change the pressures in: (a) the aortic root, coronary arteries and the left ventricle; (b) aortic root and coronary
arteries at constant ventricular pressure; and (c) the left ventricle with mean (although not pulse) aortic pressure constant.
Electrophysiological recordings were made from slips dissected from the vagus nerve which responded with an increase in discharge
to either combined increases in the pressures, or to aortic root injections of veratridine. 3. Recordings were made from twenty-one
vagal afferents. On the basis of their conduction velocities, eleven were classified as non-myelinated and ten as myelinated.
4. Three non-myelinated afferents responded to veratridine injections only, three to both veratridine and combined aortic
root and ventricular pressure changes, and five to pressure changes only. Responses to pressure occurred only when ventricular
systolic pressure exceeded 30 kPa. 5. None of the myelinated afferents responded to veratridine. All showed increases in discharge
to combined increases in mean aortic root, coronary arterial and left ventricular systolic pressures, which would be graded
over a range similar to that which caused reflex changes. All were more sensitive to changes in mean coronary pressure than
to changes in ventricular systolic pressure. 6. We conclude that myelinated vagal afferent nerve fibres, which respond predominantly
to changes in mean coronary arterial pressure, are likely to be responsible for the vasodilation to the changes in mean aortic
root pressure previously reported. These fibres are probably attached to coronary arterial mechanoreceptors. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0022-3751 1469-7793 |
DOI: | 10.1113/jphysiol.1993.sp019973 |