Monocrotaline-induced structural remodeling of the intra-acinar pulmonary arteries and pulmonary hypertension

Abstract

The monocrofaline-induced structural changes of small pulmonary arteries in rat and their relationship with pulmonary hypertension and right ventricular hypertrophy were observed by determining the right ventricular systolic pressure, and by light and electron microscope and morphometry. One to 38 days after last injection of monocrotaline (MCT), a medial thickening and lumen marrrowing of the circular muscular arteries (CMA), accompanying terminal (TB) and respiratory bronchioles (RB), were found. And there after the lumen of CMA, accompanying TB, became dilated, and its medial thickness (MT) decreased, whereas the histopathologic changes of the partially muscular arteries (PMA), accompanying RB, became severe, their MT increased continuously, and finally reached the peak value on Day 50. At the first day after last MCT treatment, inflammation and muscularization were found in PMA and nonmuscular arteries (NMA), and became more severe with the cause of disease. Therefore, the intra-acinar pulmonary arteries, both CMA and PMA, increased in number while the NMA decreased in number significantly because of the structural remodeling. Four days after MCT treatment, the right ventricular systolic pressure began to rise, and reached its peak value on Day 50. Eight days after MCT injection, right ventricular hypertrophy developed, and became most significant from Day 23 to Day 30. The results suggest that structural remodeling, i.e. muscularization, of intra-acinar pulmonary arteries plays an important role in the development of pulmonary hypertension and right ventricular hypertrophy.

Keywords

monocrotaline / intra-acinar pulmonary artery muscularization / hypertension

References

[1] KayJM, et al.. Observation of the pul-monary arteries and heart weight. J Pathol Bact, 1966, 92: 385-385

[2] KayJM, et al.. Electron microscopy of crotalaria pulmonary hypertension. Thorax, 1969, 24: 511-511

[3] KamenjiR, et al.. Increase of collagen synthesis in pulmonary arteries of mo-nocrotaline treated rats. Exper, 1980, 36: 441-441

[4] FultonRM, et al.. Ventricular weight in cardic hypertrophy. Br Heart J, 1952, 14: 413-413

[5] MeyrichB, ReidL.. Development of pulmonary arterial change in rats fed crotalaria spectabilis. Am J Pathol, 1979, 94: 37-37

[6] MolteniA, et al.. Monocrotaline in-duced pulmonary endothelial dysfunc-tion in rats. Procedings of the society for experimental biology ard medicine, 1984, 176: 82-82

[7] GillespieMN, et al.. Vascular hyperres-ponsiveness in perfused lungs from monocrotaline-treated rats. Am Physiol Society, 1986, 251(20): H109-H109

[8] 1989:66.

[9] PlestineR, StonerHB. Pulmonary ed-ema In rats given monocrotaline Pyr-role. J Pathol, 1972, 106: 235-235