Question

When curare, a South American Indian arrow poison, is placed on a nerve-muscle preparation, the muscle does not contract when the nerve is stimulated, even though neurotransmitter is still being released from the nerve. Provide every possible explanation you can think of for the action of curare.

Answer 1

Curare competitively blocks acetylcholine, preventing muscle contraction when the nerve is stimulated.

Step-by-step explanation:

Curare, a South American Indian arrow poison, causes the muscle to not contract when the nerve is stimulated because it competitively blocks the action of acetylcholine, the neurotransmitter responsible for initiating muscle contraction. When curare is applied to the end-plate of a muscle fiber, it makes the muscle cell insensitive to motor-nerve impulses and direct applied acetylcholine. However, the muscle fiber membrane still responds to other stimuli, such as potassium ions and direct electrical stimulation.