Drugs and Receptors

Question 1

Pharmacokinetics:

Answer 1

What the biological system does to the drug.

Question 2

Pharmacodynamics:

Answer 2

What the drug does to the biological system.

Question 3

Affinity:

Answer 3

Tenacity or persistent ability with which the drug binds to the specific receptors on the cell membrane.

Question 4

Intrinsic activity:

Answer 4

Inherent property of the drug to impart a cellular response.

- What happens when drug –> receptor.

Question 5

Agonist:

Answer 5

Binds to and stimulates a receptor.

Question 6

Antagonist:

Answer 6

Binds to but does not stimulate a receptor (no intrinsic activity).

Question 7

Partial agonist:

Answer 7

Agents that are only partly as effective as agonists no matter the amount employed.

Question 8

Inverse agonist:

Answer 8

Agents which stabilize the receptor in its inactive form.

Question 9

Signal transduction:

Answer 9

The process by which a receptor binding initiates a cascade of biochemical events that lead to a physiological response.

Question 10

Specificity:

Answer 10

Act through single receptor type/subtype.

Question 11

Selectivity:

Answer 11

Exert single effect.

Question 12

Gs:

Answer 12

Stimulates adenylate cyclase.

- Increase cAMP.

Question 13

Gi:

Answer 13

Inhibits adenylate cyclase.

- Decrease cAMP.

Question 14

Gq:

Answer 14

Activates phospholipase C.

- Increase IP3, DAG.

Question 15

cAMP:

Answer 15

• Used as second messenger.
• Regulates activity of protein kinases (PKA).
• Inactivated by PDE.

Question 16

cGMP:

Answer 16

• Generated by guanylyl cyclase.
• NO stimulates soluble GC.
• Natriuretic peptides, guanylins stimulate membrane-spanning GC (particulate).
• Regulates activity of PKG.

Question 17

Ca2+:

Answer 17

• Second messenger.
• May involve PLC and PIP2.
• IP3, DAG.

Question 18

Transcription-related receptors:

Answer 18

• Hydrophobic ligands
  1. Ligands enter cell via passive diffusion.
  2. Bind to receptors in cytoplasm.
  3. Complex binds to specific DNA response elements.
  4. DNA transcription altered to increase/decrease synthesis of proteins.

Question 19

Desensitization:

Answer 19

Receptor downregulation.

- After sustained agonist activity.

Question 20

Supersensitization:

Answer 20

Receptor upregulation.

- After sustained antagonist activity.

Question 21

Tachyphylaxis:

Answer 21

Loss of response on repeated administration.

- Slower dissociate of the agonist from its receptor.