What is the cardiac myocyte action potential?
The cardiac action potential is a measurement of the membrane potential waveform of the cardiac myocytes signifying the electrical activity of the cell during the contraction and relaxation of the heart. Specific ionic currents contribute to each phase of the cardiac action potential (see Fig. 24-10).
What drug will prolonged phase 3 of the cardiac action potential?
Ivabradine is considered to act specifically on the sinoatrial node by inhibiting the If current (the funny current) to slow automaticity. However, in vitro studies show that ivabradine prolongs phase 3 repolarization in ventricular tissue.
What are the 4 mechanisms for regulation of ion channel gating?
The voltage-gated ion channels of the action potential are often described as having four gating processes: activation, deactivation, inactivation, and reactivation (also called ‘recovery from inactivation’).
What are the four types of ionic gates on cell membranes?
There are three main types of ion channels, i.e., voltage-gated, extracellular ligand-gated, and intracellular ligand-gated along with two groups of miscellaneous ion channels.
What are the steps in an action potential?
Usually, the stages of action potential are summarized in five steps, the first two of which are the rising and the overshoot phases. The three latter steps would be the falling, the undershoot, and the recovery phases.
What is the plateau phase of an action potential?
This “plateau” phase of the cardiac action potential is sustained by a balance between inward movement of Ca 2+ (I Ca) through L-type calcium channels and outward movement of K + through the slow delayed rectifier potassium channels, I Ks.
What are cardiac phases?
There are two phases of the cardiac cycle; diastole and systole. In the diastole phase, the heart ventricles are relaxed and the heart fills with blood.
How does a cardiac action potential work?
The cardiac action potential is a brief change in voltage ( membrane potential) across the cell membrane of heart cells . This is caused by the movement of charged atoms (called ions) between the inside and outside of the cell, through proteins called ion channels.