[Experimental high-altitude pulmonary hypertension in rabbits]

In lowland (760 m above sea level) and highland (3200 m above sea level) of Tien Shan, the measurements of blood pressure and blood flow in the large vessels as well as the mass of heart ventricles of 75 rabbits have been made. In highland, the significant changes in hemodynamics of pulmonary circulation, appeared as elevations of pulmonary arterial pressure, pressure of wedging pulmonary artery, total and arterial pulmonary vascular resistance, have been noted. Besides this, adaptation to a highland staying was associated with an increased mass of the right ventricle of the heart. The pulmonary hypertension and hypertrophy of the right ventricle incremented during the first 2 weeks of the rabbits staying in highland and stabilized at achieved high level within succeeding 1.5 months of a tested period of adaptation. Because cardiac output and cardiac index starting from the end of 2nd week of adaptation did not differ significantly from control values, it can be said with confidence that an increase of pulmonary pressure in highland is dependent on a rise of pulmonary vascular resistance. In this case, the arterial pulmonary vascular resistance elevated to a greater extent than venous one. In highland, there revealed only the mean value of correlation relationship between the level of pulmonary blood pressure and a severity of right ventricle hypertrophy. The mass of left ventricle, systemic arterial pressure and total peripheral resistance did not significantly altered in a highland environment.