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Anrep Effect
The Anrep effect is an autoregulation method in which myocardial contractility increases with afterload. It was experimentally determined that increasing afterload caused a proportional linear increase in ventricular inotropy. This effect is found in denervated heart preparations, such as the Starling Preparation, and represents an intrinsic autoregulation mechanism. Physiology Sustained myocardial stretch activates tension-dependent Na+/H+ exchangers, bringing Na+ ions into the sarcolemma. This increase in Na+ in the sarcolemma, reduces the Na+ gradient exploited by sodium-calcium exchanger (NCX), and stops them from working effectively. Ca2+ ions accumulate inside the sarcolemma as a result, and are taken up by sarco(endo)plasmic reticulum Ca2+-ATPase ( SERCA) pumps. Calcium induced calcium release (CICR) from the sarcoplasmic reticulum is thus increased upon the next activation of the cardiac myocyte. This leads to an increase in the force of contraction of the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myocardial
Cardiac muscle (also called heart muscle, myocardium, cardiomyocytes and cardiac myocytes) is one of three types of vertebrate muscle tissues, with the other two being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that constitutes the main tissue of the wall of the heart. The cardiac muscle (myocardium) forms a thick middle layer between the outer layer of the heart wall (the pericardium) and the inner layer (the endocardium), with blood supplied via the coronary circulation. It is composed of individual cardiac muscle cells joined by intercalated discs, and encased by collagen fibers and other substances that form the extracellular matrix. Cardiac muscle contracts in a similar manner to skeletal muscle, although with some important differences. Electrical stimulation in the form of a cardiac action potential triggers the release of calcium from the cell's internal calcium store, the sarcoplasmic reticulum. The rise in calcium causes the cell's my ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
