The effect of common sclerosing agents on the rabbit pleural space

New Zealand white rabbits received intrapleural instillations of either tetracycline (7, 20, and 35 mg/kg), HCI (0.01N), quinacrine (10 mg/kg), nitrogen mustard (0.2 mg/kg), bleomycin (1.5 mg/kg), or NaOH (0.5%). All sclerosing agents produced a neutrophil-predominant, exudative pleural effusion within 12 h of instillation. By 48 h the pleural fluid was predominantly mononuclear. Despite the large pH range of the sclerosing agents (tetracycline, 2.0; NaOH, 13.0), the pleural fluid pH was always between 7.40 and 7.49 during the 144-h observation period. There was no difference in protein concentration, leukocyte count, or neutrophil differential with either the 3 different doses of tetracycline or the 5 other sclerosing agents. Autopsies at 30 days showed that only the 35 mg/kg dose of tetracycline produced pleural symphysis. We concluded that the common sclerosing agents produce a similar type of pleural effusion, but only tetracycline leads to pleural fibrosis; this effect appears to be dose-dependent. The pH of the sclerosing agent per se probably has little effect on the development of pleural symphysis.