Quinidine exes action on hea by: (A) Ca+ Channel blocker, (B) Kt Channel blocker, (C) Na+ Channel opener, (D) Cl+ Channel opener
Answer is B. Refer katzung 11e p 237 * Mechanism of action Like all other class I antiarrhythmic agents, quinidine primarily works by blocking the fast inward sodium current (INa). ... The effect of blocking the fast inward sodium current causes the phase 0 depolarization of the cardiac action potential to decrease (decreased Vmax).