In a research, electrophysiologists expose cardiac cells to various substances and record how the membrane potential of the cells changes. Below is a trace from one of the tests. Which of the following substances was most likely applied to the cells at the point indicated by the arrow?

Question

In a research, electrophysiologists expose cardiac cells to various substances and record how the membrane potential of the cells changes. Below is a trace from one of the tests.  Which of the following substances was most likely applied to the cells at the point indicated by the arrow?

Quizplus · Accepted Answer

Eductional Objective: The slow influx of Na+ through funny channels, the closing of repolarizing K+ channels, and the activation of T-type Ca²⁺+ channels all contribute to the phase 4 gradual depolarization in cardiac pacemaker cells. By extending phase 4, acetylcholine and adenosine slow the rate of spontaneous depolarization in cardiac pacemaker cells.

In a Research, Electrophysiologists Expose Cardiac Cells to Various Substances