system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Phase of cardiac action potential, where calcium channels close & slow potassium channels open :
assistant
The correct answer is  In cardiac action potential Phase O - Rapid upstroke - due to fast sodium channels- Influx of Na+Phase I - Initial repolarization - fast Na channels - closePhase II - Plateau - due to calcium influx Phase III - Rapid repolarization - Calcium channels close & slow potassium channels open Phase IV - Resting membrane potential - - 90 mv