Final answer:
Potassium channel blockers prolong the repolarization phase of cardiac action potentials, affecting the heart's rhythm, while beta blockers reduce the initiation frequency of action potentials, slowing heart rate and lowering blood pressure.
Step-by-step explanation:
Potassium channel blockers, such as amiodarone and procainamide, inhibit the outflow of potassium (K+) ions through voltage-gated K+ channels during the action potential in cardiac cells. By impeding this movement, potassium channel blockers prolong the repolarization phase of the action potential, which can alter the heart's rhythm and correct certain types of cardiac dysrhythmias. Beta blockers, on the other hand, work by inhibiting adrenaline action on beta-1 receptors, leading to a decreased heart rate and lower blood pressure. They act on the pacemaker cells within the heart to decrease the rate at which action potentials are initiated, but do not directly affect the action potential propagation once it has begun. Overprescription of beta blockers can lead to excessively slow heart rates, or even heart stoppage. In summary, potassium channel blockers primarily affect the action potential's repolarization phase in cardiac cells, whereas beta blockers influence the initiation frequency of action potentials.