Cardiac myocytes (contractile cells) have a prolonged actionpotential including a plateau phase which lasts up to ~250ms. Thisis to enable a longer, sustained contraction so that the ventricleshave time to pump blood out. In order to enable this ‘plateau’phase (Phase 2):
Group of answer choices
Slow Na+ channels enable a sustained inwardNa+ current.
Slow K+ channels enable a sustained inwardK+ current, balance with Na+ efflux.
L-type Ca2+ channels enable Ca2+ influxwhich is balanced by a slight K+ efflux.
Only Na+ and K+ are involved in thisaction potential, just like a neuron, only it takes longer for thevoltage-gated K+ channels to open and repolarise thecell.
