11) Machado-Joseph disease is one of the most common hereditary spinocerebellar degenerative disorders with a wide range

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11) Machado-Joseph disease is one of the most common hereditaryspinocerebellar degenerative disorders with a wide range ofclinical manifestations. It is considered a type of lower motorneuron disease. Muscle cramps are a very frequent anddisabling factor. Experimental data suggest that there is anincreased Na+ conductance in motor neurons at resting membranepotential in patients with Machado-Joseph disease compared tonormal subjects. How could this change account for the musclecramps?
a) change in Na+ conductance would counteract effects ofdenervation-induced collateral sprouting
b) change in resting conductance would result in moredepolarized resting membrane potential (Vrest)
c) motor neurons would become more excitable leading to greateractivation of muscle d) resting membrane potential (Vrest) would becloser to thresholde) These data could not explain the muscle cramps.