BOD L9 IPC & cardioprotection pt2

Question 1

How is intrisnic apoptotis mediated and effected?

Answer 1

Mitochondria.

Involves release of cytochrome C, found within mito, in to cytoplasm.

Question 2

How does cytochrome C act within the cytoplasm to cause apoptosis?

Answer 2

Binds apaf1 in cytoplasm, which goes onto activate caspases.

Question 3

Which two antagonists inhibit apoptosis and promotes apoptotis (via modulation of cytochrome C release)

Answer 3

Bcl-2 inhibits apoptosis

Bax/Bad promotes apoptosis.

Question 4

How can Bad/Bax be targeted for pharmacological IPC

Answer 4

when phosphorylated, inhibited.

Question 5

Where is the mitoKatp channel found?

Answer 5

On the inner mitochondiral membrane (IMM).

Question 6

What happens to the inner mito membrane when the mitoKatp channel opens?

Answer 6

Decrease in membrane potential.

Depolarisation

Question 7

What is used to inhibit mitoKatp channel during studies

Answer 7

5-HD (but also influences beta-oxidation of FA’s)

Question 8

What is used to activate mitoKatp channel during studies?

Answer 8

Diazoxide. It induces pharmacological preconditioning.

Question 9

What evidence is there for the existence of mitoKatp channel?

Answer 9

Using mitoplasts (mitochondria w/ outer membrane removed) detected presence of potassium ion channel on inner membrane.

Using dyes that accumulate in mito propoertional to membrane potential, investigate effects of Katp channel openers and blockers using mito under hypoxic conditions

Question 10

What did measurements of mito membrane potential show?

Answer 10

Cells exposed to H2O2 lose staining (lose membrane potential)

But when treated with diazoxide, protection is seen against H2O2 and membrane potential remains normal.

This protective effect can also be blocked by 5-HD.

Question 11

How does the structure of mitoKatp channel differ from other Katps?

Answer 11

No evidence that any normal subunits present in mitochondria.

Confirmed by Wb & GFP-tagging.

Question 12

What is the pore-forming component of mitoK ATP?

Answer 12

ROMK

Question 13

What are three activators of mitoK ATP channel?

Answer 13

ATP, Diazoxide, PIP2

Question 14

What are two inhibitors of mitoK ATP?

Answer 14

5-HD, ADP

Question 15

What two things mean opening of mitoKATP is cardioprotective?

Answer 15

Reduces Ca2+ overload.

Calcium overload causes formation and opening of mitochondrial permeability transition pore (mPTP) which kills cell (releases cytochrome C)

opening causes increase of ROS production during IPC

but blocks ROS during reperfusion

Question 16

What role does cacium activated K channel in mito play in cardioprotection?

Answer 16

IPC blocked by inhibiting Kca channel.

Cardioprotection induced by Kca channel opener.