Answer:
The correct answer will be option D- blocking Cl channel.
Explanation:'
Quinidine is a stereoisomer of quinine derived from the bark of Cinchona plants which is used in the medication of the heart as class I antiarrhythmic agent. This alkaloid decreases the automaticity and increases the duration of the cellular action potential of the heart.
This alkaloid acts by blocking the neurotransmission through blocking of sodium and potassium channels responsible for the depolarization in non-nodal tissues like atrial cells, ventricular cells. This decrease in the neurotransmission of an action potential depends on the Ca⁺² ions and the quinidine can also act by blocking the Ca⁺² channels as well as B adrenergic receptor.
Thus, option D-blocking Cl channel is the correct answer.
