Question
A patient under anesthesia develops hyperthermia and generalized muscle rigidity. Genetic testing reveals RYR1 gene mutation. Which ion channel is implicated in this condition?
| A. |
Sodium channel
|
| B. |
Calcium channel
|
| C. |
Potassium channel
|
| D. |
Chloride channel
|
Show Answer
|
Correct Answer � B
Explanation
|
|
– The condition described is Malignant Hyperthermia (MH), a severe reaction to certain anesthetic agents (e.g., halothane, sevoflurane) or succinylcholine.
– MH is linked to mutations in the RYR1 gene, affecting the calcium release channel in skeletal muscle.
– In affected individuals, anesthetics trigger uncontrolled calcium release from the sarcoplasmic reticulum, causing:
– Sustained muscle contraction & rigidity
– ↑ metabolism & oxygen consumption
– Excessive heat production (hyperthermia)
– Rhabdomyolysis, hyperkalemia, & metabolic acidosis
Treatment:
– Stop the triggering agent immediately.
– Administer Dantrolene, which inhibits calcium release from the ryanodine receptor.
Incorrect Options:
– A. Sodium channel mutations → hyperkalemic periodic paralysis & congenital myotonias.
– C. Potassium channel defects → long QT syndromes & periodic paralysis.
– D. Chloride channel mutations → myotonia congenita (Thomsen/Becker disease).
