A 33-year-old man comes to the office for a health checkup. He has no prior medical problems and does not take any medications. The patient works as a fitness trainer and lifts weights recreationally. He has been consuming carbohydrate-rich food prior to his weightlifting sessions and claims that it increases muscle strength. A literature review shows that the rate of glycogenolysis within myocytes increases several hundredfold during active skeletal muscle contraction. Which of the following substances is most likely responsible for increasing the reaction rate during active contraction?

Question

A 33-year-old man comes to the office for a health checkup.  He has no prior medical problems and does not take any medications.  The patient works as a fitness trainer and lifts weights recreationally.  He has been consuming carbohydrate-rich food prior to his weightlifting sessions and claims that it increases muscle strength.  A literature review shows that the rate of glycogenolysis within myocytes increases several hundredfold during active skeletal muscle contraction.  Which of the following substances is most likely responsible for increasing the reaction rate during active contraction?

Quizplus · Accepted Answer

Eductional Objective: Synchronization of glycogen degradation with skeletal muscle contraction occurs due to release of sarcoplasmic calcium following neuromuscular stimulation.  Increased intracellular calcium causes activation of phosphorylase kinase, stimulating glycogen phosphorylase to increase glycogenolysis.

A 33-Year-Old Man Comes to the Office for a Health