To observe pathological and ultrastructure changes in pulmonary vessels and right ventricular systolic pressure in rat by smoke exposure.

A total of fourty male SD rats were randomly assigned into control group and smoke exposure group and the latter was further divided into three time points of 1, 2, 3 months.Arterial oxygen partial pressure and right ventricular systolic pressure (RVSP) were observed.Ultrastructure of small pulmonary arteries was observed by transmission electron microscope.Pulmonary arteries pathological changes were observed by Hematoxylin-Eosin staining.The radio of pulmonary vessel wall′s area and pulmonary vessel′s area (WA%) were measured by image analysis system.Immunohistochemistry methods were used to determine alpha-smooth muscle actin (α-SMA) expression.

(1)Arterial oxygen partial pressure of four groups were respectively (96.2±4.3) mmHg (1 mmHg=0.133 kPa), (92.1±5.2) mmHg, (90.5±4.1) mmHg, (89.6±4.8) mmHg, there were no statistically difference between each group (all P>0.05). (2)The RVSP in group S3m (65.63±5.6) mmHg were significantly higher than those in group S1m (16.85±1.26) mmHg and group C (14.07±4.18) mmHg (allP<0.05). (3)Ultrastructure changes of intra-acinar pulmonary arteries: intimal layer in control group showed no increased so as endothelial cells and collagen fiber.Observation showed degeneration and distortion of endothelial cells and proliferation of smooth muscle cells in group in one-month smoke group, mitochondria in the endothelial cells could also be observed swelled.The internal elastic laminar was irregular, smooth muscle was observed irregular and fracture, collagen fibers increased in two-month smoke group.The organizational structure showed disordered in three-month smoke group, endothelial cells severely deformed.The muscularized arteries were observed, the hyperplasia of intermediate cells was present.Collagen fibers increased dramatically.(4)The pulmonary artery WA% of four groups (C, S1m, S2m, S3m) were (31.29±1.95)%, (42.68±2.24)%, (51.84±2.38)%, (62.11±1.39)%.Compared with control group, there were significant increases in smoke exposure groups (allP<0.01). (5)The α-SMA protein expressions of pulmonary artery walls of (C, S1m, S2m, S3m) were respectively (37.5±7.5), (52.6±14.3), (72.2±13.6), (98.1±15.6). Compared with control group, there were significant increases in smoke exposure groups (P<0.01). (6) WA% were positively correlated with α-SMA protein expressions of pulmonary artery walls.

Smoke exposure could induce obvious pathological changes and ultrastructural changes and causing arteries remodeling, leading to an increase in right ventricular systolic pressure.

Hypertension, pulmonary; Smoke; Pulmonary vascular remodeling; Ultrastructural pathology