Final answer:
Voltage-gated Na+ channels become inactivated, preventing any further influx of Na+ ions into the cell.
Step-by-step explanation:
When voltage-gated Na+ channels become inactivated, they are temporarily unable to open in response to a signal. This occurs after the peak of depolarization during an action potential. The inactivation gate of the channel closes, preventing any further influx of Na+ ions into the cell.