Ca+ and K+ channels

Question 1

Why are Ca+ targeted during lethal injection?

Answer 1

Ca channels present at neuromuscular junctions, present in heart (inhibition causes heart to stop pumping)

Question 2

What are the 5 ‘classical’ types of CaV? Why don’t we use these types anymore?

Answer 2

L-type (long lasting)
P-type (purkinje)
N-type (neural)
R-Type (residual)
T-Type (transient)

We have since discovered the genes that encode the channels and we use those instead (CaVX.Y)

Question 3

Describe the structure of a Ca channel in terms of subunits

Answer 3

Alpha1 channel is always the pore no matter the type

Ancillary subunits modulate behaviour

Question 4

What differentiates a NaV from a CaV?

Answer 4

slight amino acid differences (leads to a huge shift in selectivity)

Question 5

How is channel opening in a CaV different from a NaV? What is a use of this?

Answer 5

CaVs stay open longer, which allows for signalling instead of just depolarization

Question 6

How are CaVs so selective for Ca instead of Na?

Answer 6

Three sites with high and low affinities for Ca strip off the water molecules selectively,

Question 7

How are CaVs involved in addiction?

Answer 7

CaV expression depends on amount of stimulation

in this case the VTA contains lots of dopamine neurons, so when cocaine is consumed it causes a massive depolarization and more CaVs are presented (which is why you become addicted to cocaine but not an orgasm)

Question 8

What is the current hypothesis of Parkinson’s Disease involving CaVs?

Answer 8

Overstimulation of pathways leads to their degeneration

Question 9

What causes epileptic seizures in the context of CaVs?

Answer 9

Too much excitation/not enough inhibition

Question 10

What are the three potassium channel families? What do they look like?

Answer 10

Shaker-type: 6 TMs with pore between S5-S6)
Inward rectifiers: Two TMs with a pore between them
2P background channels: Pores between S1-S2 and S3-S4

Question 11

What is a consequence of the 3 types of KV domains? How is this useful in determining the type of a neural tissue sample?

Answer 11

Many types of K Channel

You can determine what kind of neuron you’re looking at its firing mechanism which is determined by KVs

Question 12

What pore mechanism is most similar to the KV?

Answer 12

CaV

Question 13

Why is the drug industry interested in affecting KVs?

Answer 13

Many different applications/targets on the channel

Question 14

What symptoms would you treat with a drug that affects CaVs?

Answer 14

Pain
Epilepsy
Drug addiction
Parkinsonism

Question 15

How do pain APs travel?

Answer 15

Via CaVs