The Cardiopulmonary Structures And Plateau Adaptation Of The Tibetan Sheep

Tibetan sheep is one of the three original breeds in China,and lives in the in the northwestern plateau,showed a great adaptation for the hypoxia and high cold.Normally,exposing to hypoxia and low pressure causespathological phenomena such as pulmonary hypertension and right heart hypertrophy,but tibetan sheep showed great adaptation.In order to compare the structures of the heart and lung between the tibetan sheep and small-tailed han sheep,and discuss tibent sheep adaptation to hypoxia,the left and right atria/ventricles,bronchies and lung tissues of the two sheep breeds were collected Respectively,and the methods of HE,PATH,Gommer Aldehyde fuchsin and Masson trichrome were used to observe the characteristics of the heart and lung tissue structure and conduction system.The HIF-1?(hypoxia inducible factor1?),HSP70(heat shock protein 70)and AQP1(aquaporin 1)were detected by immunohistochemistry and real-time fluorescence quantitative PCR.The results following:1.The wall thickness,the area of cardiac cavity,the lengthand diameter of cardiac fibers in left ventricle and right atrium were significantly higher in the tibetan sheep than those in the small-tailed han sheep(P<0.05).The endocardium thickness of left ventricle,right ventricle and right atrium in the tibetan sheep were significantly higher than that in the small-tailed han sheep(P<0.05).The epicardium thickness of right atrium in the tibetan sheep was significantly thicker than that in the smal-tailed han sheep(P<0.05).2.HIF-1?protein was expressed in cardiomyocytes and mainly located in the cytoplasm,showed in the nucleus of the right atrium cardiomyocytes.HIF-1?expressed in the right atrium of the two sheep breeds from high altitude area were significantly higher than that from the low altitude area.Cardiomyocyte HIF-1?expression showed no significant difference between the tibetan sheep and the small-tailed han sheep from the same altitude area.3.HSP70 were detected mostly in the cardiomyocyte nucleus of the tibetan sheep and the small-tailed han sheep,it was significantly higher in the right ventriculum than other parts of haert in both sheep breeds.And in the tibetan sheep right ventricle,HSP70 were expressed significantly stronger than that in smal-tailed han sheep(P<0.05).4.The bronchioles numbers of the tibetan sheep right lung was significantly higher than that of the small-tailed han sheep.The proportion of elastic fibers in serosa of the tibetan sheep was significantly higher than that of the small-tailed han sheep,and the numbers of gobletcells per 1mm~2 of the bronchiole epithelium of the tibetan sheep was significantly higher than that of the small-tailed han sheep.Gobletcells were detected even in terminal bronchioles in the tibetan sheep while not detectable in the small-tailed han sheep terminal bronchioles.Thickness of the terminal and respiratory bronchiole smooth muscle and the number of alveolar capillaries 1mm~2 in the tibetan sheep were significantly higher than that of the small-tailed han sheep.While the thickness of the alveolar wall was significantly lower than that of the small-tailed han sheep.The vascular smooth muscle content of pulmonary arterioles(d<100?m)in the tibetan sheep was significantly lower than that in the smal-tailed han sheep.5.In both sheep breeds,HIF-1?was mainly expressed in alveolar epithelial cells,bronchiolar mucosal epithelium and vascular endothelialium cytoplasm,and also detected in the nucleus.The expression of HIF-1?in lung of the tibetan sheep was significantly stronger than that of the small-tailed han sheep.AQP1 was mainly expressed in the alveolar epithelial cells membrane and also detected in the lung capsule and bronchiole mucosa.The expression of AQP1 in lung of the tibetan sheep was significantly higher than that of the small-tailed han sheep,and the expression in lung of the tibetan sheep from high altitude area was significantly higher than that from low altitude,but there was no significant difference between the smal-tailed han sheep from different altitude areas.Conclusions:In order to adapt to the plateau environment,the heart and lung of Tibetan sheep had adaptive structural changes.For example,the thicker myocardial wall,the larger cardiac cavity area and the coarser and longer myocardial fibers,the more abundant and deve loped bronchial goblet cel s and the thicker bronchial smooth muscle appeared in the lung.The expression of HIF-1?,HSP70,and AQP1 in heart and/or lung of the tibetan sheep were higher than that of the small-tailed han sheep..And the expression of HIF-1?in the lung was significantly higher in the lung than that in the heart.