Physiology If sodium channel inactivation is prolonged then which property of nerve conduction is hampered? A Decreased relative refractory period B Increased conduction blockade C Increased upward stroke velocity D Decreased downward stroke velocity of refractory period. 💡 Explanation If sodium channel inactivation is prolonged then which property of nerve conduction is hampered? ✓ Correct Answer: C. Increased upward stroke velocity