Do pacemaker cells have a resting potential?

Do pacemaker cells have a resting potential?

• A. No resting potential
• B. Yes; true resting potential
• C. Resting potential present only under autonomic influence
• D. Varied resting potential

Answer: (A)

Pacemaker cells lack a stable resting membrane potential. Between beats they undergo a gradual, spontaneous depolarization known as the pacemaker potential, which steadily brings the membrane to threshold and triggers the next action potential. This diastolic depolarization is driven mainly by the funny current (If) through funny channels, along with calcium influx and reduced potassium efflux, and it is modulated by autonomic input to change the rate rather than to create a true resting state. Because there is no fixed resting potential, these cells continually drift toward threshold, enabling automatic rhythmic firing.

Pacemaker cells lack a stable resting membrane potential. Between beats they undergo a gradual, spontaneous depolarization known as the pacemaker potential, which steadily brings the membrane to threshold and triggers the next action potential. This diastolic depolarization is driven mainly by the funny current (If) through funny channels, along with calcium influx and reduced potassium efflux, and it is modulated by autonomic input to change the rate rather than to create a true resting state. Because there is no fixed resting potential, these cells continually drift toward threshold, enabling automatic rhythmic firing.