What changes do anti-arrhythmic drugs induce in cardiac cells?

Anti-arrhythmic drugs primarily influence cardiac cells by altering the ion exchange processes. These medications work by modifying the movement of ions across the cell membranes of cardiac cells, which directly affects the electrical activity of the heart. By doing so, they can help restore normal heart rhythm and prevent irregularities in heartbeats.

The mechanism often involves interactions with various ion channels, such as sodium, potassium, and calcium channels. For instance, some anti-arrhythmic drugs may block sodium channels, thus slowing down the depolarization phase of the cardiac action potential. Others may affect potassium channels, leading to prolonged repolarization. By modulating these ion currents, anti-arrhythmic drugs can help to stabilize the electrical activity of the heart, making them effective in treating various types of arrhythmias.

The other options do not accurately describe the primary effects of anti-arrhythmic medications. While they might have indirect consequences on heart size, vascular tone, or oxygen consumption, these are not their primary mechanisms of action. The main focus of anti-arrhythmic therapy is to directly impact the ionic movements that underlie cardiac electrical function.