Drugs - Enzymes And Transporters 16.11.23

Question 1

What is an enzyme inhibitor?

Answer 1

An enzyme inhibitoris a molecule that binds to anenzymeand (normally) decreases itsactivity.

Question 2

What are the 2 types of enzyme inhibitors?

Answer 2

Irreversible inhibitors and reversible inhibitors

Question 3

How do irreversible inhibitors work?

Answer 3

Irreversible inhibitors usually react with the enzyme and change it chemically (e.g. viacovalent bondformation).

Question 4

How do reversible inhibitors work?

Answer 4

Reversible inhibitors bindnon-covalentlyand different types of inhibition are produced depending on whether these inhibitors bind to theenzyme, the enzyme-substrate complex, or both.

Question 5

Give 2 examples of a medication which are an enzyme inhibitor

Answer 5

Statins (blocks rate limiting step in cholesterol pathway)

ACE inhibition for lowering blood pressure,

Question 6

What are the 3 main types of protein ports in cell membranes?

Answer 6

Uniporters

Symporters

Antiporters

Question 7

How do uniporters transport molecules through cell membranes?

Answer 7

Use energy from ATP to pull molecules in

Question 8

How do symporters transport molecules through cell membranes?

Answer 8

Use the movement in of one molecule to pull in another molecule against a concentration gradient

Question 9

How do antiporters transport molecules through cell membranes?

Answer 9

One substance moves against its gradient, using energy from the second substance (mostly Na+, K+ or H+) moving down its gradient.

Question 10

Give an example of a symporter

Answer 10

Na-K-Cl co-transporter (NKCC)

Question 11

Define epithelial (sodium) channel (ENaC)

Answer 11

An (apical) membrane-bound heterotrimeric* ion channel selectively permeable to Na+ ions

*two set of three proteins

Question 12

Where and what ions are transported via epithelial (sodium) channel (ENaC)

Answer 12

Causes reabsorption of Na+ ions at the collecting ducts of the kidney’s nephrons (also in colon, lung and sweat glands)

Question 13

What drug blocks Epithelial (Sodium) channel (ENaC)

Answer 13

Amiloride (high affinity diuretic)

Question 14

Where are voltage-gated (calcium) channels found?

Answer 14

Voltage-gated ion channels (VDCC) are found in the membrane of excitable cells (e.g., muscle, glial cells, neurons, etc.)

Question 15

At physiological or resting membrane potential, are Voltage-gated (Calcium) channels normally open or closed?

Answer 15

Normally closed at resting membrane potential

Question 16

When are Voltage-gated (Calcium) channels normally opened?

Answer 16

They are activated (i.e., opened) at depolarized membrane potentials (action potential)*.

A momentary change in electrical potential on the surface of a nerve or muscle cell, that occurs when it is stimulated, resulting in the transmission of an electrical impulse.

Question 17

What drug blocks voltage-gated (calcium) inhibition?

Answer 17

Amlodipine - Amlodipine is an angioselective (Why is that important?) Ca channel blocker that inhibits the movement of Ca ions into vascular smooth muscle cells and cardiac muscle cells

This inhibits the contraction of cardiac muscle and vascular smooth muscle cells

Amlodipine inhibits Ca ion influx across cell membranes, with a greater effect on vascular smooth muscle cells

Causes vasodilation and a reduction peripheral vascular resistance, thus lowering blood pressure

Also prevents excessive constriction in the coronary arteries