True statement regarding malignant hypehermia is:: (A) Increased Ca++ transpo T-type calcium channels in T-tubules, (B) Increased Ca++ transpo T-type calcium channels in L-tubules, (C) Increased Ca++ transpo L-type calcium channels in T-tubules, (D) Increased Ca++ transpo L-type calcium channels in L-tubules
Answer is C. Malignant hypehermia is a genetic disorder; there is a defect in the gene that codes for the protein ryanodine receptor (RyR) in skeletal muscle. Ryanodine receptor is a Ca2+-release channel present in the membrane of L-tubule of skeletal muscle. When it couples with dihydropyridine receptor (DHPR)from T Tubules , there is release of Ca2+ into the sarcoplasm, initiating muscle contraction.So Increased Ca++ transpo L-type calcium channels in T-tubules leads to malignant hypehermia DHPR is an L-type voltage-sensitive Ca2+ channel. Rarely inhalational anaesthetics can cause A malignant hypehermia manifesting as muscle rigidity, sweating and masseteric spasm