Abstract
The mammalian carotid body in the neck is a chemoreceptor that senses O 2 levels in the circulatory system and adjusts the respiratory rate accordingly. When O 2 becomes scarce, large-conductance calcium-sensitive potassium (BK) channels become inhibited, which causes cell depolarization and a cascade of responses that ultimately increases ventilation. Williams et al . (see the Perspective by Hoshi and Lahiri) now find that hemoxygenase-2 (HO-2) acts as an O 2 sensor to control BK channel activity. At normal O 2 concentrations, HO-2 uses O 2 as a substrate to generate carbon monoxide (CO), a critical channel activator. During hypoxia, when O 2 becomes scarce, HO-2 activity and CO generation fall, which inhibits BK channels and results in carotid body excitation. S. E. J. Williams, P. Wootton, H. S. Mason, J. Bould, D. E. Iles, D. Riccardi, Chris Peers, P. J. Kemp, Hemoxygenase-2 is an oxygen sensor for a calcium-sensitive potassium channel. Science 306 , 2093-2097 (2004). [Abstract] [Full Text] T. Hoshi, S. Lahiri, Oxygen sensing: It's a gas! Science 306 , 2050-2051 (2004). [Summary] [Full Text]
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