Excitable cells and muscle contraction (Talbot)

Question 1

differences in skeletal muscle AP and neuronal AP

Answer 1

skeletal muscle rest in potential is about -90 mV (compared to neuronal -60 mV) due to increased K+ gradient and increased Cl- gradient (due to CIC-1 family of chloride channels allowing for leakage of Cl- –> contributes to the resting potential

skeletal muscle does not hyper polarize like neuronal AP (because skeletal Vm is so close to Ek)

defects in the CIC channel will lead to myotonia because the cell membrane won’t be able to depolarize–> this channel is very important in repeated stimulation

excitation contraction coupling in muscle cell –> depolarization causes contraction because AP is coupled to release of Ca2+ from the SR. Ca2+ causes the cell to contract