What is the function of NCX?
Sodium-calcium exchange (NCX) is the major calcium (Ca) efflux mechanism of ventricular cardiomyocytes. Consequently the exchanger plays a critical role in the regulation of cellular Ca content and hence contractility.
How does sodium calcium exchanger work?
It uses the energy that is stored in the electrochemical gradient of sodium (Na+) by allowing Na+ to flow down its gradient across the plasma membrane in exchange for the countertransport of calcium ions (Ca2+). A single calcium ion is exported for the import of three sodium ions.
Does sodium calcium exchanger use atp?
9.1 Sodium–Calcium Exchangers. The sodium–calcium exchanger (NCX) is a transmembrane protein that exchanges one calcium ion per three sodium ions. The direction of ion flux is dependent on a number of factors including pH, sodium concentrations, Ca2+ concentrations, and ATP levels.
What kind of transport is NCX?
Secondary Active Transport Mechanisms
Secondary Active Transport Mechanisms Are Symports or Antiports. The Na–Ca exchanger, NCX, described above is an example of an antiport. It has this description because the two materials being transported go in opposite directions. Such a device is also called an exchanger or a counter-transporter.
What is Phospholamban in cardiac muscle?
Phospholamban, also known as PLN or PLB, is a micropeptide protein that in humans is encoded by the PLN gene. Phospholamban is a 52-amino acid integral membrane protein that regulates the calcium (Ca2+) pump in cardiac muscle cells.
How does calcium leave the heart?
In heart muscle cells, most of the calcium is stored inside a chamber named the sarcoplasmic reticulum. The calcium in the sarcoplasmic reticulum is released during heart muscle contraction and transported back inside the sarcoplasmic reticulum during relaxation.
How does sodium ions affect the heart?
Heart rate increases after removing potassium (up to 7 bpm) and also after calcium perfusion (up to 11 bpm) whereas restoring pH slows heart beat (up to 6 bpm). Extracellular sodium has no significant influence, but the heart rate strictly depends on intracellular sodium concentration (5 bpm/mM).
Does calcium depolarize cardiac cells?
Once the threshold potential is reached, L-type calcium channels open, calcium ions enter the cell, and depolarization occurs. In contrast to the cardiac myocyte action potential, there is no inward movement of sodium ions during depolarization.
How do Antiporters work?
Antiporters, however, work by carrying a solute into or out of the cell, using the electrochemical gradient of the second solute, which is travelling in the opposite direction.
What is the role of phospholamban in muscle contraction and relaxation?
The overall effect of phospholamban is to decrease contractility and the rate of muscle relaxation, thereby decreasing stroke volume and heart rate, respectively.