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Responses of group III and IV muscle afferents to distension of the peripheral vascular bed
1 Laboratoire de Physiologie, Faculté de Médecine de Nancy, 54505 Vandoeuvre-lès-Nancy, France; and 2 Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, California 95616 This study was undertaken to test the hypothesis that group III and IV affer...
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Published in: | Journal of applied physiology (1985) 1999-08, Vol.87 (2), p.545-553 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Subjects: | |
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Online Access: | Get full text |
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Summary: | 1 Laboratoire de Physiologie,
Faculté de Médecine de Nancy, 54505 Vandoeuvre-lès-Nancy, France; and
2 Division of Cardiovascular
Medicine, Department of Internal Medicine, University of
California, Davis, California 95616
This study was undertaken to test the hypothesis that group III
and IV afferents with endings in skeletal muscle signal the distension
of the peripheral vascular network. The responses of these
slowly conducting afferents to pharmacologically induced vasodilation
and to acute obstruction of the venous drainage of the hindlimbs were
studied in barbiturate-anesthetized cats. Afferent impulses arising
from endings in the triceps surae muscles were recorded from the
L 7 and
S 1 dorsal roots. Fifteen of the 48 group IV and 3 of the 19 group III afferents tested were stimulated by
intra-aortic injections of papaverine (2-2.5 mg/kg). Sixty-two percent of the afferents that responded to papaverine also responded to
isoproterenol (50 µg/kg). Seven of the 36 group IV and 2 of the 12 group III afferents tested were excited by acute distension of the
hindlimb venous system. Four of the seven group IV afferents responding
to venous distension also responded to papaverine (57 vs. 13% for the
nonresponding). Finally, we observed that most of the group IV
afferents that were excited by dynamic contractions of the triceps
surae muscles also responded either to venous distension or to
vasodilatory agents. These results are consistent with the histological
findings that a large number of group IV endings have their receptive
fields close to the venules and suggest that they can be stimulated by
the deformation of these vascular structures when peripheral
conductance increases. Moreover, such a mechanism offers the
possibility of encoding both the effects of muscle contraction through
intramuscular pressure changes and the distension of the venular
system, thereby monitoring the activity of the veno-muscular pump.
venous distension; muscle vasodilation; ventilatory and circulatory
control; gas-exchange regulation |
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ISSN: | 8750-7587 1522-1601 |
DOI: | 10.1152/jappl.1999.87.2.545 |