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CARDIOPULMONARY EFFECTS IN AWAKE RATS FOUR AND SIX MONTHS AFTER EXPOSURE TO METHYL ISOCYANATE
Citation:
Tepper, J., M. Wiester, D. Costa, W. Watkinson, AND M. Weber. CARDIOPULMONARY EFFECTS IN AWAKE RATS FOUR AND SIX MONTHS AFTER EXPOSURE TO METHYL ISOCYANATE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-87/371 (NTIS PB88224399), 1987.
Description:
Cardiopulmonary function was assessed four and six months after Fischer-344 rats were exposed for 2 hr to 0, 3, or 10 ppm methyl isocyanate (MIC). Minute ventilation (VE) during CO2 challenge was increased in MIC-treated rats compared to controls suggesting a ventilation/perfusion inequality. An increase in maximum expiratory flow and a decrease in expiratory time indicated increased lung recoil. Evidence of pulmonary hypertension was observed in electrocardiograms (ECGs) and supported by postmortem analysis. Six months after exposure to MIC the increase in VE was no longer detectable. Forced expiratory flow-volume curves indicated persistent airway obstruction; however, no changes in inspiratory or expiratory resistance were evident. Decreased dynamic compliance and changes in two new measures of lung function, volume, and time at zero expiratory intrapleural pressure, suggest that MIC lung dysfunction also exhibited elements of a restrictive disease.