GI transporters

Question 1

Where does the most transport occur in the GI tract?

Answer 1

Specific, transport of nutrients and water occurs primarily in the jejunum

Question 2

What pump is used for HCl secretion?

Answer 2

H+: H+/K+ ATPase

Cl-: via a carrier

Question 3

Omeprazole

Answer 3

PPI- inhibits the H/K ATPase transporter; reduces the protein pumping

Question 4

Histamine antagonists

Answer 4

block the cAMP dependent pathway

Question 5

Osmolarity

Answer 5

After digestion it becomes hyperosmolar and draws lots of water into the GI lumen.

Question 6

Water flow/SECRETION through cells via?

Answer 6

Aquaporins 1 & 3

Question 7

Adenyly cyclase contributes to dehydration via?

Answer 7

Bacteria activates the adenylyl cyclase pump turning on cAMP thus providing Cl- ability to move into the lumen and water follows (cholera toxin)

Question 8

Adsorption in the small intestine relies on??

Answer 8

Electrochemical gradient of Na+

Question 9

Micelles contain?

Answer 9

bile salts, monoglycerides, fatty acids, phospholipids and cholesterol

Question 10

Chylomicrons

Answer 10

built up in the cells and exocytose to the lumen of the lymphatic system

Question 11

MCT-1 Lactate transporter

Answer 11

bacteria break down lactose if lactase is absent

Question 12

Transporters involved in drug adsorption-

Answer 12

Major drug transporter proteins are expressed at the intestinal epithelia and basolateral surface; some ARE EFFLUX TRANSPORTERS!!!

Question 13

The drug uptake is regulated by:

Answer 13

1. regulatory elements controlling the protein levels
2. genetic polymorphisms affecting activity
3. presence/administration of transport inhibitors (grapefruit juice)