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Acute hypoxic pulmonary vasoconstriction: a model of oxygen sensing
E D Michelakis1, S L Archer, E K Weir
1Department of Medicine, Veterans Administration Medical Center, Minneapolis, USA.
Physiological Research
|January 1, 1995
Summary
Hypoxia causes pulmonary vasoconstriction by altering cell redox status and reducing outward potassium currents. Systemic vessels may vasodilate due to different potassium channel responses to hypoxia.
Area of Science:
- Physiology
- Molecular Biology
- Cardiovascular Research
Background:
- Hypoxic pulmonary vasoconstriction (HPV) is a critical physiological response.
- The precise molecular mechanisms of HPV and systemic responses to hypoxia are not fully elucidated.
Purpose of the Study:
- To explore the molecular mechanisms underlying hypoxic pulmonary vasoconstriction.
- To compare the effects of hypoxia on pulmonary and systemic vascular smooth muscle cells.
Main Methods:
- The study discusses proposed mechanisms involving cellular redox status.
- It examines the role of potassium (K+) channels and calcium (Ca+2) influx.
- Comparative analysis of K+ channel expression in pulmonary and systemic arteries is considered.
Main Results:
- Hypoxia shifts pulmonary artery smooth muscle cells towards a reduced redox state, decreasing outward K+ current, causing depolarization, and leading to Ca+2 influx and vasoconstriction.
- Systemic vessels may exhibit vasodilation through hypoxia-induced opening of ATP-sensitive and Ca+2-dependent K+ channels.
- Different K+ channel expressions likely mediate distinct pulmonary and systemic vascular responses to hypoxia.
Conclusions:
- The oxygen sensing mechanisms in various cell types, including pulmonary artery smooth muscle cells, carotid body type 1 cells, and neuroepithelial bodies, show striking similarities.
- Molecular mechanisms for sensing hypoxia are likely highly conserved and tightly regulated across different cell types.