How would exposure to dendrotoxin affect somatic motor neuron activity?

• A. It would inhibit the initiation of an action potential.
• B. It would shorten the refractory period.
• C. It would prolong the action potential.
• D. It would prevent depolarization.

Answer: (C)

Dendrotoxin is a potent neurotoxin that primarily affects voltage-gated potassium channels in neurons. When somatic motor neurons are exposed to dendrotoxin, the inhibition of these potassium channels interferes with the normal process of repolarization after an action potential has occurred. Consequently, the action potential is extended, resulting in a prolonged depolarization phase.

This prolonged depolarization can lead to increased excitability of the neuron, making it difficult for the neuron to return to its resting state. In this context, motor neurons might continue to fire action potentials or fail to reset properly after firing, leading to abnormal signaling in the neuromuscular junction and potentially causing muscle spasms or sustained contraction.

Understanding the action of dendrotoxin provides insight into its effects on neuronal activity and the fundamental principles of action potential kinetics within somatic motor neurons.