Question

The drug scopolamine is used to treat dizziness, motion sickness, and smooth muscle spasms. When isolated muscle cells are incubated with scopolamine, addition of acetylcholine no longer depolarizes the muscle cell membrane or stimulates muscle cell contraction. Which would best explain how scopolamine exerts its muscle-relaxing effects?

(A) It inhibits the opening of voltage-gated K+ channels.
(B) It inhibits the transporters that pump Na+ into the muscle cell cytosol during an action potential.
(C) It inhibits the opening of Ca2+ channels in the sarcoplasmic reticulum.
(D) It inhibits the opening of acetylcholine-gated Na+ channels in the muscle cell membrane.
(E) It inhibits the transporters that pump Ca2+ into the muscle cell cytosol during an action potential.

Answer 1

Answer:

The correct answer is D it inhibits the opening of Acetyl choline gated Na+ channels in the muscle cell membrane.

Explanation:

Scopolamine is an Anticholinergic drug because it perform its function by blocking the activity of the neurotransmitter Acetyl Choline.

      Acetyl choline is a neurotransmitter that help in the generation of postsynaptic potential by depolarization process which deals with the opening of Na+ ion channels.

                     As Scopolamine inhibits the depolarization of muscle it does the same by inhibiting the opening of Acetyl choline gated Na+ channels in the muscle cell membrane.