Repolarising currents of VCM

Question 1

I(to)

Answer 1

I(to)1 = 2 Ca-insensitive K channels

I(to)2 = Ca-sensitive Cl- channel

Initial notch of repolarisation
Activated by the upstroke
Inactivated while cell is still depolarised

Question 2

IKr and IKs, some IKur (mainly in atria, purkinjes)

Answer 2

Gradually activate to generate outward current

Question 3

Ik1

Answer 3

• High conductance inward rectifier current
• Responsible for rising potential that is approaching equilibrium potential for K
• Activated at more repolarised point than other repolarisation channels
• This allows AP to have a long plateau before fully repolarising