Here are some questions to help focus your study efforts for the mid-term exam to be given in class on Thursday 17 March, 2005.
(1) What is the difference between outward rectification and delayed rectification?
(2) What is the difference between inactivation and deactivation of INa. When would you observe inactivation, and when deactivation?
(3) What are tail currents and how are they evoked? Under what conditions are they observed?
(4) Explain why Hodgkin and Huxley proposed raising gating variables m and n to exponential powers m^3 and n^4, respectively, in their model of membrane excitability
(5) How does delayed rectifier current affect membrane excitability? Specifically address how voltage dependence and kinetics are involved.
(6) How does A-current affect membrane excitability? Specifically address how the voltage dependence and kinetics are involved.
(7) Why are SK channels involved in AP repolarization and a long-lasting phase of hyperpolarization (where Vm dips below Vrest for several hundred milliseconds to 1 sec), whereas BK channels are associated with AP repolarization only.
(8) Why is the M-current associated with controlling repetitive discharge behavior (i.e., whether or not it can occur at all, as well as the rate of repetitive firing when it is possible)?
(9) compare and contrast the electrophysiological properties of IK-IR and Ih with respect to ion permeability, voltage-dependence, mechanism of gating, and kinetics.
(10) p.198 of KL discusses results in Aplysia SNs where perfusion of the catalytic subunit of PKA causes prolonged all-or-none closures of K+ channels. they propose that channel closure is due to a PKA-mediated phosphorylation reaction "since the frequency of the kinase-induced closures are reduced three- to fourfold in the absence of ATP." How do these data support their proposal?
(11) p.200 of KL explains how cytoplasmic inhibitor proteins act in concert with PKA to potentiate/augment the S-channel closure function of 5-HT?
(12) Explain how serotonin affects the I-V curve and membrane behavior of R15 neurons of Aplysia.