Abstract
We examined the contribution of afferent vagal A- and C-fibers on abdominal expiratory muscle activity (EMA). In seven spontaneously breathing supine dogs anesthetized with α-chloralose we recorded the electromyogram of the external oblique muscle at various vagal temperatures before and after the induction of a pneumothorax. When myelinated fibers were blocked selectively by cooling the vagus nerves to 7°C, EMA decreased to 40% of control (EMA at 39°C). With further cooling to 0°C, removing afferent vagal C-fiber activity, EMA returned to 72% of control. On rewarming the vagus nerves to 39°C, we then induced a pneumothorax (27 ml/kg) that eliminated the EMA in all the dogs studied. Cooling the vagus nerves to 7°C, during the pneumothorax, produced a slight though not significant increase in EMA. However, further cooling of the vagus nerves to 0°C caused the EMA to return vigorously to 116% of control. In three dogs, intravenous infusion of a constant incrementally increasing dose of capsaicin, a C-fiber stimulant, decreased EMA in proportion to the dose delivered. These results suggest that EMA is modulated by a balance between excitatory vagal A-fiber activity, most likely from slowly adapting pulmonary stretch receptors, and inhibitory C- fiber activity, most likely from lung C-fibers.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1795-1800 |
| Number of pages | 6 |
| Journal | Journal of Applied Physiology |
| Volume | 71 |
| Issue number | 5 |
| State | Published - 1991 |
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Keywords
- C-fibers
- external oblique
- pneumothorax
- slowly adapting pulmonary stretch receptors
- vagus nerve
ASJC Scopus subject areas
- Endocrinology
- Physiology
- Orthopedics and Sports Medicine
- Physical Therapy, Sports Therapy and Rehabilitation
Cite this
Role of vagal afferents in the control of abdominal expiratory muscle activity in the dog. / Hollstien, S. B.; Carl, M. L.; Schelegle, Edward S; Green, J. F.
In: Journal of Applied Physiology, Vol. 71, No. 5, 1991, p. 1795-1800.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Role of vagal afferents in the control of abdominal expiratory muscle activity in the dog
AU - Hollstien, S. B.
AU - Carl, M. L.
AU - Schelegle, Edward S
AU - Green, J. F.
PY - 1991
Y1 - 1991
N2 - We examined the contribution of afferent vagal A- and C-fibers on abdominal expiratory muscle activity (EMA). In seven spontaneously breathing supine dogs anesthetized with α-chloralose we recorded the electromyogram of the external oblique muscle at various vagal temperatures before and after the induction of a pneumothorax. When myelinated fibers were blocked selectively by cooling the vagus nerves to 7°C, EMA decreased to 40% of control (EMA at 39°C). With further cooling to 0°C, removing afferent vagal C-fiber activity, EMA returned to 72% of control. On rewarming the vagus nerves to 39°C, we then induced a pneumothorax (27 ml/kg) that eliminated the EMA in all the dogs studied. Cooling the vagus nerves to 7°C, during the pneumothorax, produced a slight though not significant increase in EMA. However, further cooling of the vagus nerves to 0°C caused the EMA to return vigorously to 116% of control. In three dogs, intravenous infusion of a constant incrementally increasing dose of capsaicin, a C-fiber stimulant, decreased EMA in proportion to the dose delivered. These results suggest that EMA is modulated by a balance between excitatory vagal A-fiber activity, most likely from slowly adapting pulmonary stretch receptors, and inhibitory C- fiber activity, most likely from lung C-fibers.
AB - We examined the contribution of afferent vagal A- and C-fibers on abdominal expiratory muscle activity (EMA). In seven spontaneously breathing supine dogs anesthetized with α-chloralose we recorded the electromyogram of the external oblique muscle at various vagal temperatures before and after the induction of a pneumothorax. When myelinated fibers were blocked selectively by cooling the vagus nerves to 7°C, EMA decreased to 40% of control (EMA at 39°C). With further cooling to 0°C, removing afferent vagal C-fiber activity, EMA returned to 72% of control. On rewarming the vagus nerves to 39°C, we then induced a pneumothorax (27 ml/kg) that eliminated the EMA in all the dogs studied. Cooling the vagus nerves to 7°C, during the pneumothorax, produced a slight though not significant increase in EMA. However, further cooling of the vagus nerves to 0°C caused the EMA to return vigorously to 116% of control. In three dogs, intravenous infusion of a constant incrementally increasing dose of capsaicin, a C-fiber stimulant, decreased EMA in proportion to the dose delivered. These results suggest that EMA is modulated by a balance between excitatory vagal A-fiber activity, most likely from slowly adapting pulmonary stretch receptors, and inhibitory C- fiber activity, most likely from lung C-fibers.
KW - C-fibers
KW - external oblique
KW - pneumothorax
KW - slowly adapting pulmonary stretch receptors
KW - vagus nerve
UR - http://www.scopus.com/inward/record.url?scp=0025934203&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0025934203&partnerID=8YFLogxK
M3 - Article
C2 - 1761476
AN - SCOPUS:0025934203
VL - 71
SP - 1795
EP - 1800
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
SN - 8750-7587
IS - 5
ER -