Journal of Applied Physiology, Vol 53, Issue 4 873-878, Copyright © 1982 by American Physiological Society
Cerebrovascular responses to CO2 after inhibition of sympathetic activity
A. L. Lopez de Pablo, M. C. Gonzalez, G. Dieguez, B. Gomez and S. Lluch
The effects of inhalation of 10% CO2 in air on cerebral blood flow (CBF)
and cerebrovascular resistance (CVR) were examined in 13 unanesthetized
goats before and after impairment of the sympathetic activity present in
cerebral vessels. Under control conditions, inhalation of CO2 increased CBF
from 112 +/- 10.2 (SE) to 191 +/- 17.2 ml X min-1 X 100 g-1 and decreased
CVR from 0.91 +/- 0.02 to 0.55 +/- 0.03 Torr X ml-1 X min X 100 g. After
treatment with reserpine CO2 increased CBF to levels similar to those
before treatment, but values for CVR were significantly lower. Inhalation
of CO2 1-2 days after removal of both superior cervical sympathetic ganglia
produced a larger increase in CBF and a greater drop in CVR, whereas at
6-20 days after ganglionectomy the effects of CO2 were analogous to those
measured before the operation. The results suggest that the existence of an
intact tonic adrenergic activity is a factor in the level of CVR achieved
in hypercapnic acidosis.
