Sympathetic transduction to blood pressure following three days in hypobaric hypoxia: Influence of nocturnal periodic breathing.

We investigated whether three days of hypoxic exposure in a hypobaric chamber, and the associated nocturnal periodic breathing (nPB), reduce sympathetic nerve activity (MSNA) transduction to blood pressure (BP). While hypoxia did not affect MSNA transduction to BP, larger drops in BP occurred following cardiac cycles without sympathetic bursts, suggesting increased reliance on sympathetic vasoconstrictor support for beat-to-beat BP. Prevention of nPB by inspiratory carbon dioxide administration did not affect MSNA transduction to BP in hypoxia.