Hindlimb muscular contraction reflexly decreases total pulmonary resistance in dogs

M. P. Kaufman, K. J. Rybicki, J. H. Mitchell

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

We have previously shown that contraction of the gracilis muscles of anesthetized dogs reflexly relaxes tracheal smooth muscle. We have also found that electrical stimulation of these afferents decreases total pulmonary resistance (TPR), a calculation that provides a functional index of airway caliber. Despite these findings, we have yet to show that muscular contraction reflexly decreases TPR. Therefore, in 11 α-chloralose-anesthetized dogs, we contracted the hindlimb muscles by electrically stimulating the L6-L7 ventral roots while measuring TPR breath by breath. We found that static contraction decreased TPR from 12.6 ± 1.1 to 10.4 ± 0.9 cmH2O·1-1·s (P<0.05). This decrease was reflex in origin because it was prevented by section of the spinal roots innervating the working hindlimb. Repetitive twitch contractions (5 Hz) also reflexly decreased TPR, but the effect was smaller than that evoked by static contraction. The reflex decreases in TPR evoked by contraction were unaffected by propranolol but were abolished by atropine. We conclude that muscular contraction dilates the airways by a reflex mechanism whose efferent arm consists of a withdrawal of cholinergic input to airway smooth muscle.

Original languageEnglish (US)
Pages (from-to)1521-1526
Number of pages6
JournalJournal of Applied Physiology
Volume59
Issue number5
StatePublished - 1985

Fingerprint

Hindlimb
Muscle Contraction
Dogs
Lung
Reflex
Spinal Nerve Roots
Smooth Muscle
Chloralose
Atropine
Propranolol
Cholinergic Agents
Electric Stimulation
Muscles

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Hindlimb muscular contraction reflexly decreases total pulmonary resistance in dogs. / Kaufman, M. P.; Rybicki, K. J.; Mitchell, J. H.

In: Journal of Applied Physiology, Vol. 59, No. 5, 1985, p. 1521-1526.

Research output: Contribution to journalArticle

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