Which statement correctly describes KATP channels?

Which statement correctly describes KATP channels?

• A. KATP channels are activated by ATP, open during hypoxia
• B. KATP channels are inhibited by ATP, closed during hypoxia
• C. KATP channels are inhibited by ATP, open when ATP decreases during hypoxia
• D. KATP channels are activated by acetylcholine

Answer: (C)

KATP channels couple the cell’s energy state to its electrical activity. ATP binding keeps these channels closed; when energy is low, such as during hypoxia, intracellular ATP falls and the channels open. Opening allows K+ to exit, hyperpolarizing the cell membrane and shortening the action potential, which reduces Ca2+ entry and helps lower energy demand in cardiac cells during stress. Acetylcholine does not directly activate KATP channels in the heart; its main effect is slowing the heart via muscarinic receptors and GIRK channels. So, these channels are inhibited by ATP and open when ATP decreases during hypoxia.

KATP channels couple the cell’s energy state to its electrical activity. ATP binding keeps these channels closed; when energy is low, such as during hypoxia, intracellular ATP falls and the channels open. Opening allows K+ to exit, hyperpolarizing the cell membrane and shortening the action potential, which reduces Ca2+ entry and helps lower energy demand in cardiac cells during stress. Acetylcholine does not directly activate KATP channels in the heart; its main effect is slowing the heart via muscarinic receptors and GIRK channels. So, these channels are inhibited by ATP and open when ATP decreases during hypoxia.