Ventilation during acute HCl infusion in intact and chemodenervated conscious rabbits

The ventilatory response to acute (0-90 min) intravenous infusion of HCl was studied in awake, conscious rabbits with intact (CB+) and denervated (CB-) carotid bodies. The HCl dose was delivered such as to produce an increasing degree of acidosis over 90 min reaching blood pH values of 7.032-7.115 at 60-90 min and plasma [HCO-3] values of 8.5-10.6 mmol . L-1 . CB- rabbits exhibit an increase in VT by 7 min and a decrease in PaCO2 by 15 min of infusion, changes that increased over 90 min. However, at all times the CB- response was significantly less than that in CB+ rabbits. The relationships, percent decrease in PaCO2 vs delta [H+] and percent increase VT vs delta [H+], were well approximated by linear regression analysis in both CB+ and CB- groups and the slope, as an index of the response sensitivity, was, in CB- rabbits, 0.33-0.37 of that in CB+ rabbits. In the conscious, awake rabbit, peripheral chemoreceptors seem to account for up to 2/3 of the ventilatory response to metabolic acidosis.