What is the mechanism behind the increased temperature in malignant hyperthermia?

What is the mechanism behind the increased temperature in malignant hyperthermia?

• A. Excessive use of ATP to sequester the calcium that was released
• B. Increased heat production from uncoupled oxidative phosphorylation
• C. Decreased ATP production due to mitochondrial failure
• D. Increased peripheral vasodilation causing heat loss

Answer: (A)

Malignant hyperthermia causes a surge of calcium release from the sarcoplasmic reticulum in skeletal muscle. That calcium triggers continuous muscle contraction, and restoring calcium to its storage requires a lot of ATP. The ATP is used by the Ca2+-ATPase pumps to resequester calcium and by the contractile machinery (myosin ATPase) to sustain contraction. This enormous ATP hydrolysis produces a lot of heat, driving the marked hyperthermia. Other ideas don’t fit the mechanism: heat from uncoupled oxidative phosphorylation isn’t the primary driver here, ATP production isn’t decreased but taxed by excessive demand, and vasodilation would promote heat loss rather than heat gain.

Malignant hyperthermia causes a surge of calcium release from the sarcoplasmic reticulum in skeletal muscle. That calcium triggers continuous muscle contraction, and restoring calcium to its storage requires a lot of ATP. The ATP is used by the Ca2+-ATPase pumps to resequester calcium and by the contractile machinery (myosin ATPase) to sustain contraction. This enormous ATP hydrolysis produces a lot of heat, driving the marked hyperthermia. Other ideas don’t fit the mechanism: heat from uncoupled oxidative phosphorylation isn’t the primary driver here, ATP production isn’t decreased but taxed by excessive demand, and vasodilation would promote heat loss rather than heat gain.