心・腎血行動態と血中および心筋・腎組織内カテコラミンに及ぼす低酸素負荷の影響

Abstract

A study was performed on anesthetized dogs to investigate the changes in hemodynamics, plasma catecholamine concentrations and catecholamine stores in the heart muscle and kidney during experimental hypoxia induced by breathing a mixed gas of 5% O₂ and 95% N₂ by artificial ventilation. During hypoxia, aortic blood pressure and cardiac output successively increased. Renal blood pressure increased and renal blood flow decreased, resulting in increased renal vascular resistance. Catecholamine stores in the heart muscle and kidney were significantly lower in the hypoxic breathing group than in the non-hypoxic group. Marked increases in noradrenaline and adrenaline concentrations in blood from the aorta, coronary sinus and renal vein were observed. The degree of increase in noradrenaline concentration was higher in coronary sinus and renal vein blood than in aortic blood, and the degree of increase in adrenaline concentration was higher in aortic blood. The decline in catecholamine stores in the heart and kidney of the hypoxic breathing group is suspected to be due mainly to degeneration of the sympathetic nerve fibers distributed in the heart muscle and kidney. This release of catecholamines from nerve fibers may account for the increase of catecholamines in coronary sinus and renal vein blood and hemodynamic changes.