Abstract des Autors

The density of beta-adrenergic receptors in circulating lymphocytes was evaluated in a group of 14 healthy, non-endurance-trained students subsequent to a 14 days ski-mountaineering class at an altitude of 1700-3000 m. Binding studies with the radioligand 3H-dihydroalprenolol showed a 25% reduction in beta-receptor number per cell without alterations in the dissociation constant. No changes in cell number of polymorphonuclear leucocytes or lymphocyte subsets were found. Baseline sympathetic activity measured by nocturnal catecholamine excretion was characterized by elevated noradrenaline values during the early phase of altitude exposure without alterations in adrenaline excretion. Overall, these data suggest that longer lasting activation of the sympathetic nervous system due to physical activity under altitude conditions leads to a desensitization of beta-adrenergic receptors on blood lymphocytes. Verf.-Referat