What is Proteolysis in CIM?

What is Proteolysis in CIM?

• A. Selective protein myosin motor filament loss after sepsis or SIRS
• B. Global decrease in muscle mass
• C. Loss of collagen in tendons
• D. Conversion of muscle to fat

Answer: (A)

Proteolysis in CIM refers to active breakdown of muscle proteins, especially the myosin heavy chain that forms the motor filaments essential for contraction. In critical illness, signals from inflammation and stress (such as sepsis or SIRS) trigger proteolytic pathways, notably the ubiquitin-proteasome system and calpains, leading to selective loss of myosin and other contractile proteins. This targeted degradation reduces the amount of functional motor proteins, causing weakness that can be out of proportion to nerve function and without an immediate, global collapse of muscle mass. That selective loss of myosin motor filaments after sepsis or SIRS is the hallmark described here. Other options describe more general or unrelated changes, not the specific proteolytic targeting of the contractile apparatus seen in CIM.

Proteolysis in CIM refers to active breakdown of muscle proteins, especially the myosin heavy chain that forms the motor filaments essential for contraction. In critical illness, signals from inflammation and stress (such as sepsis or SIRS) trigger proteolytic pathways, notably the ubiquitin-proteasome system and calpains, leading to selective loss of myosin and other contractile proteins. This targeted degradation reduces the amount of functional motor proteins, causing weakness that can be out of proportion to nerve function and without an immediate, global collapse of muscle mass. That selective loss of myosin motor filaments after sepsis or SIRS is the hallmark described here. Other options describe more general or unrelated changes, not the specific proteolytic targeting of the contractile apparatus seen in CIM.