Physiology What is the ionic basis for after depolarization in a record of an AP? A Entry of Ca++ slow channels. B Late entry of Na+ channels that have been activated. C Altered gradient for K+ movement. D Prolonged open state of K+ channels. 💡 Explanation What is the ionic basis for after depolarization in a record of an AP? ✓ Correct Answer: C. Altered gradient for K+ movement.