Does acute hypoxia alter the sensitivity of arterial baroreflex control of heart rate and sympathetic vasoconstrictor outflow in healthy humans?
Acute hypoxia resets baroreflex control of heart rate and sympathetic activity to higher pressures without altering baroreflex sensitivity in healthy humans.
We tested the hypothesis that acute hypoxia would alter the sensitivity of arterial baroreflex control of both heart rate and sympathetic vasoconstrictor outflow. In 16 healthy, nonsmoking, normotensive subjects (8 women, 8 men, age 20-33 yr), we assessed baroreflex control of heart rate and muscle sympathetic nerve activity by using the modified Oxford technique during both normoxia and hypoxia (12% O(2)). Compared with normoxia, hypoxia reduced arterial O(2) saturation levels from 96.8 +/- 0.3 to 80.7 +/- 1.4% (P 0.05). Acute exposure to hypoxia reset baroreflex control of both heart rate and sympathetic activity to higher pressures without changes in baroreflex sensitivity.
Halliwill et al. (Sun,) studied this question.
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