The Anrep effect is an autoregulation method in which

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 ...

contractility Contractility refers to the ability for self-contraction, especially of the muscles or similar active biological tissue *Contractile ring in cytokinesis *Contractile vacuole *Muscle contraction **Myocardial contractility *See contractile cell for ...

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 The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to t ...

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 The sarcolemma (''sarco'' (from ''sarx'') from Greek; flesh, and ''lemma'' from Greek; sheath) also called the myolemma, is the cell membrane surrounding a skeletal muscle fiber or a cardiomyocyte. It consists of a lipid bilayer and a thin oute ...

. This increase in Na⁺ in the sarcolemma, reduces the Na⁺ gradient exploited by

sodium-calcium exchanger The sodium-calcium exchanger (often denoted Na+/Ca2+ exchanger, exchange protein, or NCX) is an antiporter membrane protein that removes calcium from cells. It uses the energy that is stored in the electrochemical gradient of sodium (Na+) by al ...

(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 SERCA, or sarco/endoplasmic reticulum Ca2+-ATPase, or SR Ca2+-ATPase, is a calcium ATPase-type P-ATPase. Its major function is to transport calcium from the cytosol into the sarcoplasmic reticulum. Function SERCA is a P-type ATPase. It reside ...

) pumps.

Calcium induced calcium release Ryanodine receptors (RyR for short) form a class of intracellular calcium channels in various forms of excitable animal tissue like muscles and neurons. There are three major isoforms of the ryanodine receptor, which are found in different tissu ...

(CICR) from the sarcoplasmic reticulum is thus increased upon the next

activation Activation, in chemistry and biology, is the process whereby something is prepared or excited for a subsequent reaction. Chemistry In chemistry, "activation" refers to the reversible transition of a molecule into a nearly identical chemical o ...

of the cardiac myocyte. This leads to an increase in the force of contraction of the

cardiac muscle 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 th ...

, which partly counterbalances the effects of afterload by increasing stroke volume and cardiac output to maintain tissue perfusion. On the other hand, it has been proposed that the Anrep effect may be a spurious effect resulting from the recovery of the myocardium from a transient ischemia arising from the abrupt increase in blood pressure.

Function

The Anrep effect allows the heart to compensate for the increased

end-systolic volume End-systolic volume (ESV) is the volume of blood in a ventricle at the end of contraction, or systole, and the beginning of filling, or diastole Diastole ( ) is the relaxed phase of the cardiac cycle when the chambers of the heart are re-fil ...

and the decreased stroke volume that occurs when aortic blood pressure (i.e. afterload) increases. Without the Anrep effect, an increase in aortic blood pressure would create a decrease in stroke volume that would compromise circulation to peripheral and visceral tissues.

History

The Anrep effect is named after

Russian Russian(s) refers to anything related to Russia, including: *Russians (, ''russkiye''), an ethnic group of the East Slavic peoples, primarily living in Russia and neighboring countries *Rossiyane (), Russian language term for all citizens and peo ...

physiologist Gleb von Anrep, who described it in 1912. Anrep clamped the ascending aorta in

dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. Do ...

s, and showed that the heart dilated.

References

{{reflist Cardiology