Stimulation of vagal afferents inhibits locomotion in mesencephalic cats

J. G. Pickar, J. M. Hill, Marc P Kaufman

Research output: Contribution to journalArticle

39 Scopus citations

Abstract

Using electrical stimulation of the mesencephalic locomotor region, we made decerebrate unanesthetized cats walk on a treadmill. The locomotion induced by stimulation of this midbrain area was assessed before and during activation of vagal afferents by either intravenous injection of phenylbiguanide or inflation of a balloon placed in the left atrium. Inflation of a balloon, which increased left atrial pressure by 7-25 mmHg, abolished locomotion in 9 of 10 cats tested. Bilateral cervical vagotomy prevented the abolition of locomotion by balloon inflation in each of two cats tested. Intravenous phenylbiguanide (50 or 100 μg/kg) or serotonin (40 μg/kg) injections abolished or attenuated walking induced by midbrain stimulation in 11 of 13 cats tested. In addition, intravenous phenylbiguanide injections abolished or attenuated locomotion with a shorter onset time than did systemic injections of this substance in five of six cats tested. Bilateral cervical vagotomy prevented the abolition of locomotion by phenylbiguanide injection in each of five cats tested. We conclude that locomotion can be prevented by a viscerosomatic reflex arising from the lungs and heart. The afferent arm of this reflex arc is the vagus nerve. Afferents such as slowly and rapidly adapting pulmonary stretch receptors, atrial receptors, and lung C-fibers may have had a role in preventing locomotion during the increase in left atrial pressure in our experiments. On the other hand, pulmonary C-fibers had a crucial role in preventing locomotion during intravenous injection of phenylbiguanide. We speculate that this viscerosomatic reflex may help to explain in part the intolerance for exercise displayed by patients with congestive heart failure.

Original languageEnglish (US)
Pages (from-to)103-110
Number of pages8
JournalJournal of Applied Physiology
Volume74
Issue number1
StatePublished - 1993

Keywords

  • exercise
  • heart failure
  • J-reflex
  • locomotion
  • pulmonary C-fibers

ASJC Scopus subject areas

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

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