TY - JOUR
T1 - Stimulation of vagal afferents inhibits locomotion in mesencephalic cats
AU - Pickar, J. G.
AU - Hill, J. M.
AU - Kaufman, M. P.
PY - 1993
Y1 - 1993
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0027499129&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0027499129&partnerID=8YFLogxK
U2 - 10.1152/jappl.1993.74.1.103
DO - 10.1152/jappl.1993.74.1.103
M3 - Article
C2 - 8444680
AN - SCOPUS:0027499129
SN - 0161-7567
VL - 74
SP - 103
EP - 110
JO - Journal of applied physiology
JF - Journal of applied physiology
IS - 1
ER -