To investigate whether the transcriptional activator hypoxia-inducible factor 1 (HIF-1) is required for ventilatory responses to hypoxia, we analyzed mice that were either wild type or heterozygous for a loss-of-function (knockout) allele at the Hif1a locus, which encodes the O2-regulated HIF-1α subunit. Although the ventilatory response to acute hypoxia was not impaired in Hif1a+1- mice, the response was primarily mediated via vagal afferents, whereas in wild-type mice, carotid body chemoreceptors played a predominant role. When carotid bodies isolated from wild-type mice were exposed to either cyanide or hypoxia, a marked increase in sinus nerve activity was recorded, whereas carotid bodies from Hif1a+1- mice responded to cyanide but not to hypoxia. Histologic analysis revealed no abnormalities of carotid body morphology in Hif1a+1- mice. Wild-type mice exposed to hypoxia for 3 days manifested an augmented ventilatory response to a subsequent acute hypoxic challenge. In contrast, prior chronic hypoxia resulted in a diminished ventilatory response to acute hypoxia in Hif1a+1- mice. Thus partial HIF-1 α deficiency has a dramatic effect on carotid body neural activity and ventilatory adaptation to chronic hypoxia.
|Original language||English (US)|
|Number of pages||6|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - Jan 22 2002|
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