Functional residual lung capacity in rats affected by a carotid body stimulant.

The respiratory response and changes of functional residual lung capacity were measured in the rat after intravenous administration of the drug S 2620 in a dose of 0.4 mg/kg. This substance induced a significant decrease of arterial PCO2 and an increase of minute ventilation. The stimulating effect of S 2620 was maximal in the 10th min; after 60 min, ventilation and PCO2 approached control levels. The CO2 ventilatory response was determined 10 min after the administration of S 2620. The slope of the control and S 2620 stimulated curves was similar with a shift towards higher ventilation and lower PCO2 after S 2620 administration. Functional capacity rose with increasing minute ventilation. The increase of functional residual capacity disappeared after bilateral cervical vagotomy.