Repolaritáció

Repolarizáció refers to the recovery phase of a muscle cell, particularly a neuron or cardiac myocyte, after excitation. During an action potential, the cell membrane undergoes depolarization, a rapid influx of positive ions that makes the inside of the cell positive relative to the outside. Following depolarization, repolarization is the process by which the cell membrane potential returns to its resting negative state.

This restoration of the resting membrane potential is primarily achieved by the outward movement of potassium ions (K+) from the cell. After the voltage-gated sodium channels (Na+) that caused depolarization inactivate, voltage-gated potassium channels open, allowing K+ to flow down its electrochemical gradient out of the cell. This efflux of positive charge makes the inside of the cell more negative.

In cardiac cells, repolarization is a critical event that is visually represented on an electrocardiogram (ECG) as the T wave. Disruptions in repolarization can lead to serious cardiac arrhythmias. In neurons, proper repolarization is essential for the neuron to be able to fire another action potential and for the transmission of nerve impulses. The duration and characteristics of repolarization can be influenced by various factors, including ion channel function and the presence of certain drugs.