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Unformatted text preview: which helps maintain a normal (hyperpolarized) cell membrane potential. What is the chemical messenger that acts on BK channels to keep them open during normoxia? CARBON MONOXIDE (Its a Gas!) This is one of the key concepts in the Williams, et al. hypothesis. Several of you thought it was calcium. 3. What molecule is the oxygen sensor that produces the chemical messenger? HEMOXYGENASE-2 (HO-2) 4. What happens to BK channels when the arterial P O2 decreases below 90-100 mm Hg? THE BK CHANNELS CLOSE; CO keeps them open when the P O2 is high enough. 5. What effect does the change in the BK channels due to decreased P O2 have on the glomus cell? THE MEMBRANE IS DEPOLARIZED (The answer I was looking for and which most of you gave.). Increased frequency of action potentials, influx of calcium ions or release of dopamine were also acceptable responses. Some of you listed all four....
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- Fall '08