Contractility Proteins


 Creative BioMart Contractility Proteins Product List
 Contractility Proteins Background

Cardiac contractility

The force to maintain cardiac output is generated by contraction and relaxation of cardiomyocytes. The central regulator of cardiac contractility is the common second messenger Ca2+. Altering the Ca2+ transient and altering the sensitivity of the myofilaments to Ca2+ are two main ways to increase the strength of cardiac contraction. Ca2+ generates its signals by changing intracellular concentrations maintained by pumps, exchangers, and channels. In cardiomyocytes, there is a large internal store of Ca2+ in the sarcoplasmic reticulum (SR), which is induced to release a large amount of Ca2+ following a small increase of extracellular Ca2+ into the cytosol. Increased cytosolic Ca2+ concentration initiates contraction by inducing conformational changes in myofilament proteins. That Ca2+ must then be removed from the cytosol to allow for relaxation. The decreased contractility associated with heart failure is likely the result of alterations in myocyte Ca2+ regulation and/or alterations in contractile proteins.

Cardiac contractility

Ca2+ is the central regulator of cardiac contractility. As illustrated in the top section, Ca2+ generates signals by changing internal and external concentrations. In the heart there is a large internal store of Ca2+ in the SR. During contraction (middle section), a small increase of extracellular Ca2+, mediated by the L-type Ca2+ channel, induces a much larger release of Ca2+ into the cytosol from the SR. Increased cytosolic Ca2+ initiates contraction by binding its effector TnC allowing for crossbridge formation. Ca2+ removal in relaxation (bottom section) is carried out primarily by the action of SERCA2a and NCX, although the extent that each contributes varies between species.