Exam #1: Smooth Muscle Drugs

Question 1

What is the mechanism behind Calcium Antagonists?

Answer 1

Block voltage-gated Ca2+ channels, reducing influx of Ca2+

Question 2

What is the mechanism behind Potassium Channel Openers?

Answer 2

Increase K+ concentration inside the cell causing hyperpolarization → reduced ability to open Ca2+ voltage-gated channels

Question 3

What is the mechanism behind B2 Adrenergic Receptor Agonists?

Answer 3

Stimulates cAMP production

- cAMP inhibits MLCK even in the presence of increased intracellular Ca2+

Question 4

What is the mechanism behind Nitrates?

Answer 4

Stimulates cGMP production

- cGMP activates MLCP and decreases intracellular Ca2+

Question 5

What is the mechanism behind Phosphodiesterase Inhibitors?

Answer 5

Inhibits the degradation of cGMP (by phosphodiesterase)

- cGMP is present longer to activate MLCP and decrease intracellular Ca2+

Question 6

What do all of the drugs in this deck result in?

Answer 6

Relaxation of smooth muscle

Question 7

What is the function of cAMP?

Answer 7

Inhibits MLCK

Question 8

What is the function of cGMP? How is it produced (substrate and enzyme)?

Answer 8

Activates MLCP AND decreases intracellular Ca2+

- cGMP comes from nitric oxide (NO) via guanylate cyclase (GC)