The effects of aerosols of carbamylcholine, serotonin and propranolol on the ventilatory response to CO2 in guinea pigs and comparison with the effects of histamine and sulfuric acid.

A new method is introduced to recognize the acute pulmonary effect of airborne contaminants in guinea pigs. The method avoids anaesthesia and invasive techniques and requires minimal restraint of the animal. To recognize the acute pulmonary effect, the inspiratory volume of the animal was increased by continuous inhalation of a mixture containing 10% CO2 in 18% O2 and 72% N2. Once a plateau increase in inspiratory volume was reached, the aerosol to be studied was added to this mixture and its effect in reducing inspiratory volume measured. By exposing the animals to different exposure concentrations of carbamylcholine, serotonin and propranolol aerosols, concentration-response relationships were obtained which permitted comparison of their potency. Comparisons were also made with histamine and sulfuric acid aerosols previously studied.