Changes of the right and left ventricles in rats exposed to intermittent high altitude hypoxia.

Significant structural, functional and metabolic differences between the right and left ventricles are present already in control animals. Intermittent high altitude (IHA) hypoxia (4 hr daily, 5 days a week, stepwise up to an altitude of 7000 m in a hypobaric chamber) induced in adult rats pulmonary hypertension and right ventricular hypertrophy; prolonged hypoxia also increased the relative left ventricular mass. Both chambers show proportionate increase in concentration of myofibrilar and collagenous proteins; the right-left difference, characteristic of animals living in normoxic environment, remains unaffected. The relative right and left ventricular bloodflow in hypoxic animals increases and so doses also the activity of glycolytic enzymes in both ventricles. Necrotic lesions, localized predominantly in the right ventricle, develop only at the beginning of adaptation to IHA. Parallel changes in the structure and enzyme activity of the myosine molecule in both ventricles can be observed. Administration of beta-blocking agent (Trimepranol, Spofa) significantly decreased pulmonary hypertension and right ventricular hypertrophy; the relative left ventricular mass normalized. Furthermore, Trimepranol significantly reduced necrotic changes in the right ventricle after a dose of 10 mg/kg, in the left ventricle - after 1 mg/kg. These results support the hypothesis of a possible impairment of left ventricular function in the presence of a primary right ventricular disturbance.