The MOST LIKELY effect of increasing the potassium conductance in a cardiac pacemaker cell would be

Increasing the potassium conductance in a cardiac pacemaker cell would most likely lead to hyperpolarization of the cell.

Here's a step-by-step explanation:

1. Potassium ions (K+) are positively charged. In a resting cardiac pacemaker cell, the concentration of K+ is higher inside the cell than outside.

2. Increasing potassium conductance means making the cell membrane more permeable to K+. This would allow more K+ to flow out of the cell.

3. As K+ ions leave the cell, they take their positive charge with them. This makes the inside of the cell more negative relative to the outside, a state known as hyperpolarization.

4. Hyperpolarization of a cardiac pacemaker cell would slow down the rate of spontaneous depolarization, which is the process that initiates each heartbeat.

5. Therefore, the most likely effect of increasing the potassium conductance in a cardiac pacemaker cell would be a decrease in heart rate.