Name 3. You are studying a potassium channel that has the same characteristics o

Question

Name 3. You are studying a potassium channel that has the same characteristics of a voltage-gated potassium channel, except that it is gated (opened) by hyperpolarization. You preform whole- cell voltage clamp experiment on a cell that is expressing these channels. You step the membrane potential from -70 mV to -120mV to activate these channels. Assume physiological concentrations of potassium and also assume that these are the only channels expressed in the cell a) Draw the response you expect to see upon hyperpolarizing the cell. b) What effect will the current you record have on the membrane potential during your voltage clamp experiment? c) What effect would the current have on the membrane potential if you were not performing a voltage-clamp experiment? (in other words, what is the physiological effect of this current)

Explanation / Answer

b. When potassium channels are activated, it has the tendancy for potassium to move out of cell creating more negativity inside. So this creates negative effects on cell.That is the upward deflection of action potential will not be seen. hence it may form a simple graded potential which cannot be propagated.

c. If voltage clamp experiment is not performed, the membrane potential will not be stepped and resting membrane potential remains at minus 70 mv and potassium channels open during the repolarization phase to terminate the action potential.

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