Question

EGTA is a substance that binds calcium ions. Imagine an experimental setup with a motor neuron and a muscle fiber. Stimulation of the motor neuron causes contraction of the muscle fiber through activity at the neuromuscular junction and excitation-contraction coupling. Now, inject the muscle fiber with EGTA. Which of the following effects would EGTA have on excitation-contraction coupling after the neuron releases acetylcholine at the neuromuscular junction?

A) It would prevent conduction of an action potential along the sarcolemma.
B) It would prevent the junctional folds from triggering an action potential.
C) It would prevent the release of calcium ions from the terminal cisterns.
D) It would prevent myosin from forming cross bridges with actin.

Answer 1

Option (4).

Step-by-step explanation:

EGTA is also known as egtazic acid that acts as a chelating agent. EGTA has the ability to bind with the calcium ions and shows chelation.

The muscle fiber is injected with EGTA (according to the experiment) will effect the excitation contraction coupling. Since, calcium ions is important for the excitation-contraction coupling after the neuron releases acetylcholine at the neuromuscular junction but EGTA chelates the calcium ions and binds with it. The crossbridge between and myosin is prevented due to the binding of calcium with EGTA.

Thus, the correct answer is option (D).