What will happen to action potential if the inactivation mec

What will happen to action potential if the ‘inactivation’ mechanism of voltage gated Na+ channel is inactivated?

Solution

When a nerve impulse reaches a voltage gated sodium channel, then the sodium channel opens up. Sodium starts moving into the membrane. As a result the membrane potential starts increasing, until it reaches the threshold potential. This is known as action potential. Due to this, the membrane becomes slightly positive on the outer side, and slightly negative on the inner side.

Now, after some time, the sodium channels close and potassium channels open. This results in export of potassium ions out of the cell; and is known as repolarization.

Now, in the above question, voltage gated Na+ channel has been inactivated. \'Inactivation\' means the channel is blocked, so that no ions can move through it. Inactivation mechanism of voltage gated Na+ channel is inactivated. So, sodium channel will not be inactivated or closed after opening.

Please note that action potential is reached, when a threshold amount of sodium ions reach the inside of the cell. Opening of potassium channels depends on voltage. In the above case, sodium channels are open. So, action potential will be reached after some time, which will further result in opening of potassium channels. So, no effect will be there in the above case on the action potential. But repolarization will not be able to occur.