Quinidine [Chemical/Ingredient] C25816 An optical isomer of quinine, extracted from the bark of the Cinchona tree and similar plant species. This alkaloid dampens the excitability of cardiac and skeletal muscles by blocking sodium and potassium currents across cellular membranes. It prolongs cellular action potential, and decreases automaticity. Quinidine also blocks muscarinic and alpha-adrenergic neurotransmission. Cinchonan-9-ol, 6'-methoxy-, (9S)- Chinidin 9068 Quinidine M0018341 Quinidine N0000007728 Quinidine D011802 C0034414 Quinolines [Chemical/Ingredient] Quinuclidines [Chemical/Ingredient] Cinchona Alkaloids [Chemical/Ingredient]