抄録
Monocrotaline, a pyrolizidine alkaloid, is known to produce hypertensive pulmonary vascular changes with right ventricular hypertrophy in some animals. The present experiment was designed to study the relation between the histopathological changes of pulmonary vasculature and the development of pulmonary hypertension in rats. Male Sprague-Dowley rats (50-70g) were given a subcutaneous injection of monocrotaline (40mg/kg). The intracardiac pressures were recorded by inserting a polyethylene catheter into the right ventricle at 7, 14, 21, 26 and 28 days after the monocrotaline injection. Compared with the normal value of right ventricular systolic pressure (RVSP) in the control, rats receiving monocrotaline showed significant elevation of RVSP:
The gradual increase in the heart wt./body wt. ratio of the test rats after 21 experimental days suggested right ventricular hypertrophy. Histologically, medial thickening of the pulmonary elastic arteries and muscular arteries and muscularisation of the pulmonary arterioles with corresponding narrowing of the lumen developed. A close correlation between the medial thickness of the pulmonary small arteries and the value of RVSP was revealed. In some animals with marked elevation of RVSP, fibrinoid degeneration of small pulmonary arterial walls and fibrin thrombi were observed. Additionally, exudative changes with mononuclear cell infiltration was observed in the alveoli and the perivascular and peribronchial areas of the lung a few days following injection. These changes converted into the enmeshed structure of the alveolar wall or apparent interstitial pneuminitis after 21 experimental days.
