A Researcher Is Studying the Electrolytes Changes During Cardiac Muscle

question 274

Multiple Choice

A researcher is studying the electrolytes changes during cardiac muscle contraction and relaxation. He also monitors the intracellular calcium regulation. Microelectrodes placed into cardiac muscle cells detect a rapid decrease in cytoplasmic calcium level immediately preceding relaxation. Which of the following proteins is most likely responsible for the observed change in electrolyte levels?

• A)Calmodulin
• B)Na⁺/Ca²⁺ exchanger
• C)Ryanodine receptors
• D)Troponin C
• E)Voltage-dependent calcium channels

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