Journal of Applied Physiology, Vol 61, Issue 1 91-97, Copyright © 1986 by American Physiological Society
Ventilatory response to phasic contraction and passive movement in graded anesthesia
W. Hida, C. Shindoh, Y. Kikuchi, T. Chonan, H. Inoue, H. Sasaki and T. Takishima
The ventilatory response to electrically induced contraction (EIC) and
passive movement (PM) of hindlimb muscles at different levels of anesthesia
was studied in 11 chloralose-urethan anesthetized dogs with and without
rhizotomy. The level of anesthesia was assessed by corneal reflexes and
measurements of the ventilatory response to hypercapnia. Muscle contraction
was induced by electrically stimulating the peripheral cut ends of the
sciatic and femoral nerves for 4-5 min, and PM was induced manually at the
same frequency and amplitude as during EIC. In spinal intact dogs (n = 7),
initial rapid increases in minute ventilation (VE) during EIC and PM were
found in both light and deep anesthesia. Further increases in VE above the
initial rise were seen during EIC but not PM. The initial rapid increases
in VE did not differ between the two anesthetic levels. The steady-state
ventilatory response during EIC decreased as anesthesia deepened but did
not do so during PM. Rhizotomy (n = 4) abolished the initial rapid increase
in VE during EIC and PM and the steady-state VE response to PM at both
anesthetic levels. These results suggest that the transitional ventilatory
response is neurally mediated from the muscles and not affected by the
level of general anesthesia. Additionally, the anesthesia-induced reduction
of ventilatory response may be due to depression of responsiveness to CO2
rather than to the inspiratory motoneuron pathway.
