Hypoxia sensing in the fetal chicken femoral artery is mediated by the mitochondrial electron transport chain

Bea Zoer, Angel L Cogolludo, Francisco Perez-Vizcaino, Jo G R De Mey, Carlos E Blanco, Eduardo Villamor

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Vascular hypoxia sensing is transduced into vasoconstriction in the pulmonary circulation, whereas systemic arteries dilate. Mitochondrial electron transport chain (mETC), reactive O(2) species (ROS), and K(+) channels have been implicated in the sensing/signaling mechanisms of hypoxic relaxation in mammalian systemic arteries. We aimed to investigate their putative roles in hypoxia-induced relaxation in fetal chicken (19 days of incubation) femoral arteries mounted in a wire myograph. Acute hypoxia (Po(2) approximately 2.5 kPa) relaxed the contraction induced by norepinephrine (1 microM). Hypoxia-induced relaxation was abolished or significantly reduced by the mETC inhibitors rotenone (complex I), myxothiazol and antimycin A (complex III), and NaN(3) (complex IV). The complex II inhibitor 3-nitroproprionic acid enhanced the hypoxic relaxation. In contrast, the relaxations mediated by acetylcholine, sodium nitroprusside, or forskolin were not affected by the mETC blockers. Hypoxia induced a slight increase in ROS production (as measured by 2,7-dichlorofluorescein-fluorescence), but hypoxia-induced relaxation was not affected by scavenging of superoxide (polyethylene glycol-superoxide dismutase) or H(2)O(2) (polyethylene glycol-catalase) or by NADPH-oxidase inhibition (apocynin). Also, the K(+) channel inhibitors tetraethylammonium (nonselective), diphenyl phosphine oxide-1 (voltage-gated K(+) channel 1.5), glibenclamide (ATP-sensitive K(+) channel), iberiotoxin (large-conductance Ca(2+)-activated K(+) channel), and BaCl(2) (inward-rectifying K(+) channel), as well as ouabain (Na(+)-K(+)-ATPase inhibitor) did not affect hypoxia-induced relaxation. The relaxation was enhanced in the presence of the voltage-gated K(+) channel blocker 4-aminopyridine. In conclusion, our experiments suggest that the mETC plays a critical role in O(2) sensing in fetal chicken femoral arteries. In contrast, hypoxia-induced relaxation appears not to be mediated by ROS or K(+) channels.

Original languageEnglish
JournalAmerican Journal of Physiology: Regulatory, Integrative and Comparative Physiology
Volume298
Issue number4
Pages (from-to)R1026-34
ISSN0363-6119
DOIs
Publication statusPublished - Apr 2010
Externally publishedYes

Keywords

  • Animals
  • Anoxia
  • Antimycin A
  • Chick Embryo
  • Electron Transport
  • Femoral Artery
  • Mitochondria
  • Nitrates
  • Norepinephrine
  • Reactive Oxygen Species
  • Rotenone
  • Tetraethylammonium
  • Vasodilation

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