A. False. Receptors that bind ligands with high affinity remain activated for prolonged periods after exposure to the ligand.
B. False. Many important drug targets are intracellular, notably DNA receptors.
C. True. Receptors are proteins and are constantly being formed and degraded, a process that allows the numbers of available receptors to be increased (up-regulation) or decreased (down-regulation), leading to altered tissue responsiveness.
D. False. G-proteins are only one of many mechanisms by which receptor binding can lead to cellular responses.
E. False. Many receptors share the same pathways and secondary messengers.
Which of the following statements concerning the decline of drug concentration over time are true?
Select true or false for each of the following statements