Acid-base balance and cardiac index in SO2-bronchitic, papaine-emphysematous and paraquat-fibrotic rats after isoproterenol treatment.

SO2-bronchitis, papaine-emphysema and paraquat fibrosis were induced in Wistar rats. Blood pressure, cardiac index, total peripheral resistance, arterial blood gas values, parameters of acid-base balance were determined. Effects of 0.1 and 0.3 microgram.-1.min-1 isoproterenol iv. infusion were examined. Morphologic alterations of the lungs were verified by histopathological examinations. All the parameters investigated were found to be normal in the control rats. The treated groups differed from the normal ones: an increased blood pressure was observed in emphysema and fibrosis. A decreased cardiac index was characteristic of chronic bronchitis, high cardiac index of emphysema, high TPR of bronchitis and arterial hypoxaemy of fibrosis. The groups reacted differently to beta adrenergic stimulation: in bronchitic and fibrotic rats the cardiac index was augmented, whereas in emphysematous ones the increase proved to be smaller. The effects of isoproterenol infusion can be related to the altered beta-receptor function in the various experimental pulmonary diseases.