Question

Curare is a chemical purified from the bark of a South American vine, Chondrodendron tomentosum. South American native hunters place the curare on arrow tips. Animals shot with these arrows die from respiratory failure. Derivatives of curare have also been developed for medical use as a muscle relaxant that causes paralysis of muscles during surgery or other procedures. In this case, the muscle cell is the postsynaptic cell. Which of the following potential drug mechanisms would fit with the main outcome of muscle paralysis?Choose one:A. competitive inhibitor of the ligand-gated ion channel on the postsynaptic cellB. agonist that leads to opening of the Ca2+ channel on the presynaptic cellC. competitive inhibitor of neurotransmitter reuptake by the presynaptic cellD. All three of these mechanisms could potentially cause muscle paralysis.

Answer 1

A. Competitive inhibitor of the ligand-gated ion channel on the postsynaptic cell

Explanation:

• The competitive inhibitor of the ligand gated ion channel will exclude the true ligand from binding to the ion channel.
• The ligand gated ion channel on the postsynaptic cell will bind to the inhibitor and thus inhibiting the transfer of ion from synaptic cleft to inside of the cell.
• The  nerve impulse will not be transmitted through it resulting in the paralyses.