Title: T-tubule - Wikipedia
Headings: T-tubule
T-tubule
Contents
Structure
Regulators
Function
Excitation-contraction coupling
Calcium control
Detubulation
History
Clinical significance
See also
References

Content: Through these mechanisms, T-tubules allow heart muscle cells to contract more forcefully by synchronising calcium release throughout the cell. T-tubule structure and function are affected beat-by-beat by cardiomyocyte contraction, as well as by diseases, potentially contributing to heart failure and arrhythmias. Although these structures were first seen in 1897, research into T-tubule biology is ongoing. Contents
1 Structure
1.1 Regulators
2 Function
2.1 Excitation-contraction coupling
2.2 Calcium control
2.3 Detubulation
3 History
4 Clinical significance
5 See also
6 References
Structure
T-tubules are tubules formed from the same phospholipid bilayer as the surface membrane or sarcolemma of skeletal or cardiac muscle cells. They connect directly with the sarcolemma at one end before travelling deep within the cell, forming a network of tubules with sections running both perpendicular (transverse) to and parallel (axially) to the sarcolemma. Due to this complex orientation, some refer to T-tubules as the transverse-axial tubular system. The inside or lumen of the T-tubule is open at the cell surface, meaning that the T-tubule is filled with fluid containing the same constituents as the solution that surrounds the cell (the extracellular fluid). Rather than being just a passive connecting tube, the membrane that forms T-tubules is highly active, being studded with proteins including L-type calcium channels, sodium-calcium exchangers, calcium ATPases and Beta adrenoceptors. T-tubules are found in both atrial and ventricular cardiac muscle cells ( cardiomyocytes ), in which they develop in the first few weeks of life. They are found in ventricular muscle cells in most species, and in atrial muscle cells from large mammals.