A 68-year-old man presents with acute substernal chest pain radiating to his left arm for 2 hours. Vital signs: BP 142/88 mmHg, HR 102 bpm, RR 20, temp 37.2°C, SpO2 98% on room air. He denies dyspnea. ECG shows ST elevation in leads II, III, aVF. Troponin I is elevated at 2.4 ng/mL. He takes aspirin and metoprolol chronically. Which ion is primarily responsible for the rapid depolarization during phase 0 of the ventricular action potential?
- A)Magnesium through T type channels
- B)Sodium through fast voltage gated channelsGABARITO
- C)Calcium through L type channels
- D)Potassium through delayed rectifier channels
- E)Chloride through ligand gated channels
Explicação
Sodium through fast voltage gated channels is correct. In ventricular myocytes and Purkinje fibers, phase 0 depolarization is mediated by rapid opening of fast sodium channels. This differs from the SA and AV nodes, where phase 0 depends mainly on calcium infl... Ver explicação completa e trilha adaptativa →