Lecture 1.7: Other Transporters

Question 1

What is the NA+Cl-K+ Transporter? Why is it important?

Answer 1

The transporter pumps Cl- and K+ into the cell and Na+ out of the cell. It makes Cl_ concentrations high in relatively immature neurons and makes the concentration relatively low in mature neurons

Question 2

How do the Na,K-ATPase, KCC2 (potassium chloride cotransporter) and GABAA R (GlyR) transport systems regulate chloride concentration in the cell?

Answer 2

The Na,K-ATPase pump creates a gradient of K+ ions whcih is then used to pump Cl_ ions out of the cell via the KCC2 cotransporter. When the GABAAR channels open up, Cl- ions flows into the cell, hyperpolarizing it.

Question 3

How does the cell regulate internal calcium concentration? Why would it want to regulate that?

Answer 3

Ca ATPase is the primary active Ca2+ transport. Na,Ca antiporter is the second example. Na+ flows in, Ca2+ flows out. Ca2+ binding proteins take them out of the free solution. Calcium is used for signaling so gated channels allow the ion in and they close, preventing further calcium influx.

Question 4

How does reduced activity of the Na,Ca pumps and Na,Ca ATPase affect the body/

Answer 4

Reduced activity can lead to ischemic tissue damage. Decreased oxygen leads to decreased ATP which leads to increased Ca2+ concentration with ultimately leads to cell death. Ischemic tissue damage is the result of the blockage of blood flow in the brain or heart.

Question 5

Explain how the xenopus oocyte experiment displays why regulation of water transport is important.

Answer 5

Injection of aquaporins (water channels) into the fish cell caused the cell to swell and burst, due to the amount of free ions in the cell.