[Effect of normobaric and hypobaric hypoxia on norepinephrine turnover in the rat heart (author's transl)].

1. After administration of 3H norepinephrine (NE), the turnover rates of NE were determined by the decrease in radioactivity. 2. Rats were housed by groups in chambers and either maintained as controls or exposed to a hypoxic environment (PIO2 = 90 torr). The turnover rates of NE were not altered by normobaric hypoxia (fig. 1, table I). 3. Hypobaric hypoxia (barometric pressure was reduced to 500 mm Hg and PIO2 was 105 torr) increased the turnover rates of NE (fig. 2, table II). 4. The role of the sympathetic nervous system during exposure to hypoxia in Rats is discussed with regard to functional adaptation.