Ion channels as drug targets

What do calcium‑channel blockers inhibit?

Voltage‑gated L‑type calcium channels.

What is the effect of calcium‑channel blockers on vascular smooth muscle?

Relaxation and vasodilation.

What is the effect of calcium‑channel blockers on the heart?

Reduced contractility and reduced heart rate.

What adverse effect is associated with amlodipine?

Ankle swelling due to arterial dilation without venous dilation.

What are membrane transport proteins?

Proteins that move ions or molecules across membranes.

What are the main classes of membrane transport proteins?

Ion channels

What is passive transport?

Movement down an electrochemical gradient without energy input.

What is active transport?

Movement against a gradient requiring ATP or ion gradients.

What are voltage‑gated ion channels?

Channels that open in response to changes in membrane potential.

What are ligand‑gated ion channels?

Channels that open when a ligand binds.

What determines ion channel selectivity?

The selectivity filter

How does amlodipine block calcium channels?

By binding within the channel and disrupting the selectivity filter.

What is IC50?

The concentration of inhibitor required to reduce activity by 50%.

What does potency mean?

The amount of drug needed to produce an effect.

What does a low IC50 indicate?

High potency.

What is selectivity?

The preference of a drug for one target over another.

What do thiazide diuretics inhibit?

The Na⁺/Cl⁻ symporter in the kidney.

How do thiazide diuretics lower blood pressure?

By increasing salt and water excretion

What is the Na⁺/K⁺ ATPase?

An ion pump that moves 3 Na⁺ out and 2 K⁺ into the cell using ATP.

What drug inhibits the Na⁺/K⁺ ATPase?

Digoxin.

How does digoxin increase cardiac contractility?

By increasing intracellular Ca²⁺ via reduced Na⁺/Ca²⁺ exchange.

What are proton pump inhibitors used for?

Reducing gastric acid secretion.

What is the difference between ion channels and ion pumps?

Channels allow passive diffusion; pumps require ATP.