| Experiments presented in this thesis using guinea pigs and rats were undertaken to better understand the pulmonary toxicity produced following exposure to paraquat, a widely used herbicide. To evaluate the pulmonary function following exposure, the CO;The acute respiratory pattern seen following exposure to paraquat was rapid, shallow breathing with an abnormally shaped rectangular flow-volume loop. The decrease in tidal volume and increase in respiratory frequency showed a concentration dependent response 18 hours following exposure when breathing room air or the CO;The decrease in tidal volume and increase in respiratory rate (rapid, shallow breathing) along with a rectangular shaped flow-volume loop are all characteristics of lung restriction (Schaper et al., 1985). The mechanism involved in producing lung restriction are numerous and include abnormalities within the lung as well as outside of the lung (Rebuck and Slutsky, 1981; 1986). One factor contributing to lung restriction which we detected with paraquat was acute histopathological changes occurring in the lung which included edema and inflammation. The stimulation of Type J receptors is known to occur with edema and inflammation and upon their stimulation rapid, shallow breathing is produced. In addition, other factors not evaluated by this research may be involved. The rapid, shallow breathing characteristic of lung restriction which we detected acutely has also been observed in humans poisoned with paraquat indicating that these animal models appear to reflect the human response. |
