The Anrep effect is an autoregulation method in which myocardial contractility increases with

afterload Afterload is the pressure that the heart must work against to eject blood during systole (ventricular contraction). Afterload is proportional to the average arterial pressure. As aortic and pulmonary pressures increase, the afterload increases on ...

. 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 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 ...

. This leads to an increase in the force of contraction of the cardiac muscle, which partly counterbalances the effects of afterload by increasing

stroke volume In cardiovascular physiology, stroke volume (SV) is the volume of blood pumped from the left ventricle per beat. Stroke volume is calculated using measurements of ventricle volumes from an echocardiogram and subtracting the volume of the blood i ...

and

cardiac output In cardiac physiology, cardiac output (CO), also known as heart output and often denoted by the symbols Q, \dot Q, or \dot Q_ , edited by Catherine E. Williamson, Phillip Bennett is the volumetric flow rate of the heart's pumping output: t ...

to maintain

tissue perfusion Perfusion is the passage of fluid through the circulatory system or lymphatic system to an organ or a tissue, usually referring to the delivery of blood to a capillary bed in tissue. Perfusion is measured as the rate at which blood is delive ...

. 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 Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" r ...

Function

The Anrep effect allows the heart to compensate for the increased end-systolic volume and the decreased stroke volume that occurs when aortic blood pressure (i.e. afterload) increases. Without the Anrep effect, an increase in aortic

would create a decrease in stroke volume that would compromise circulation to peripheral and visceral tissues.

History

The Anrep effect is named after Russian

physiologist Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical a ...

Gleb von Anrep, who described it in 1912. Anrep clamped the ascending aorta in dogs, and showed that the heart dilated.

References

{{reflist Cardiology