Repeated pulmonary function measurements in rats after intratracheal instillation of a polyamine textile pigment component

The pulmonary response of Wistar rats to a cumulative dose of 1 mg/kg body weight of a polymeric alpha,omega-diamine was examined using the intratrach eal route of administration. instillation of the test substance was on days 0 and 7 followed by a 3-month postobservation period. Static and dynamic p ulmonary function tests, including arterial blood gas determinations, were performed during wk 5, 9, and 13. At all time points, significantly depress ed flow-volume corves, reduced quasistatic compliance, and reduced vital ca pacity were observed. These tl cre associated with increases of residual vo lume and functional residual capacity in the presence of unremarkable chang es of total lung capacity (TLC). One of the most predominant dysfunctions o f the lung war a severe maldistribution of ventilation, indicated by the si ngle-breath nitrogen washout lest. The carbon monoxide diffusing capacity ( DLCO), in turn, was only mildly decreased, and differences between treatmen t and control groups did not reach statistical significance. Assessment of arterial blood gases demonstrated a statistically significantly increased v enous admixture with subsequent slight hypoxemia. In summary, the predomina nt dysfunction appeared to be consistent with an obstructive rather than re strictive lung disease. The functional changes observed may account for the effect on arterial blood gases, suggesting a mismatch of the ventilation-p erfusion relationship. Either measurement appear to demonstrate a relative stable dysfunction during the 3-mo postinstillation observation period. Col lectively, this study supports the view held that polymeric alpha,omega-dia mines appear to be potent pneumotoxicants.