O2 sensing is preserved in mice lacking the gp91 phox subunit of NADPH oxidase

S. L. Archer, H. L. Reeve, E. Michelakis, L. Puttagunta, R. Waite, D. P. Nelson, M. C. Dinauer, E. K. Weir

Research output: Contribution to journalArticle

240 Scopus citations

Abstract

The rapid response to hypoxia in the pulmonary artery (PA), carotid body, and ductus arteriosus is partially mediated by O2-responsive K+ channels. K+ channels in PA smooth muscle cells (SMCs) are inhibited by hypoxia, causing membrane depolarization, increased cytosolic calcium, and hypoxic pulmonary vasoconstriction. We hypothesize that the K+ channels are not themselves 'O2 sensors' but rather respond to the reduced redox state created by hypoxic inhibition of candidate O2 sensors (NADPH oxidase or the mitochondrial electron transport chain). Both pathways shuttle electrons from donors, down a redox gradient, to O2. Hypoxia inhibits these pathways, decreasing radical production and causing cytosolic accumulation of unused, reduced, freely diffusible electron donors. PASMC K+ channels are redox responsive, opening when oxidized and dosing when reduced. Inhibitors of NADPH oxidase (diphenyleneiodonium) and mitochondrial complex 1 (rotenone) both inhibit PASMC whole-cell K+ current but lack the specificity to identify the O2-sensor pathway. We used mice lacking the gp91 subunit of NADPH oxidase [chronic granulomatous disease (CGD) mice] to assess the hypothesis that NADPH oxidase is a PA O2-sensor. In wild-type lungs, gp91 phox and p22 phox subunits are present (relative expression: macrophages > airways and veins > PASMCs). Deletion of gp91 phox did not alter p22 phox expression but severely inhibited activated O2 species production. Nonetheless, hypoxia caused identical inhibition of whole-cell K+ current (in PASMCs) and hypoxic pulmonary vasoconstriction (in isolated lungs) from CGD vs. wild-type mice. Rotenone vasoconstriction was preserved in CGD mice, consistent with a role for the mitochondrial electron transport chain in O2 sensing. NADPH oxidase, though a major source of lung radical production, is not the pulmonary vascular O2 sensor in mice.

Original languageEnglish
Pages (from-to)7944-7949
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume96
Issue number14
DOIs
StatePublished - Jul 6 1999
Externally publishedYes

Keywords

  • Chronic granulomatous disease
  • Hypoxic pulmonary vasoconstriction
  • Iberiotoxin
  • K(v) channels
  • O radicals

Fingerprint Dive into the research topics of 'O<sub>2</sub> sensing is preserved in mice lacking the gp91 phox subunit of NADPH oxidase'. Together they form a unique fingerprint.

  • Cite this