[Effect of obsidan on the cardiovascular system under conditions of high-altitude hypoxia]

The effect of beta-adrenergic block on the circulatory reactions of a human being induced by high altitude hypoxia was studied by multi-channel rheography and indirect determination of systolic pulmonary arterial pressure. In healthy people not subjected to a pharmacological effect, 25-day stay at an altitude of 3,200 m was marked by an increase in cerebral blood flow at the beginning of adaptation and the development of pulmonary hypertension the maximum signs of which were recorded during the first days in the mountains. Daily intake of 80 mg of obsidan begun 3 days before the ascent levelled out the adaptative increase in cerebral perfusion and intensified the marked character and stability of hypoxic pulmonary vasoconstriction. It is concluded that great care should be exercised in giving obsidan at high altitude to individuals with even latent forms of right ventricular pathology since under conditions of hypobaric hypoxia beta-adrenergic block increases the load suffered by the right ventricular myocardium.