High-Altitude Hypoxia and Echocardiographic Indices of Pulmonary Hypertension in Male and Female Chickens at Adulthood

Background By combining the chick embryo model with incubation at high altitude (HA), the effects of chronic hypoxia on fetal growth, fetal cardiac and aortic wall remodeling and systemic arterial blood pressure at adulthood were reported. Using non-invasive functional echocardiography, here we investigated the in vivo effects of HA hypoxia on the pulmonary circulation at adulthood in male and female chickens. Methods and results Chick embryos were incubated, hatched and raised at sea level (SL) or at HA. At 6 months of age, functional echocardiography was performed and the body and heart weights were taken. Heart weight was heavier in males but not in female HA chickens compared to their same sex SL counterparts. Similarly, male but not female HA chickens had greater in vivo right ventricular wall thickness compared to their same sex SL counterparts. The tricuspid pressure gradient was greatly enhanced in HA male and HA female chickens. However, the increment in the tricuspid pressure gradient was greater in HA males than in HA females. The pulmonary artery diameter was also enhanced in HA males than in SL males. In contrast, HA did not affect this variable in female chickens. Conclusions The data show that chronic hypoxia during development at HA is associated with echocardiocraphic indices of pulmonary hypertension at adulthood in a highly sex-dependent manner.