Prab at 05:11, 19 March 2025

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-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 [[Ventricle (heart)|ventricular]] inotropy.<ref>{{Cite journal | last1 = Von Anrep | first1 = G. | title = On the part played by the suprarenals in the normal vascular reactions of the body | journal = The Journal of Physiology | volume = 45 | issue = 5 | pages = 307–317 | year = 1912 | pmid = 16993158 | pmc = 1512890 | doi=10.1113/jphysiol.1912.sp001553}}</ref>
+'''Anrep Effect''' is an intrinsic autoregulatory mechanism of the [[heart]], in which an increase in [[afterload]] leads to an increase in [[myocardial]] [[contractility]]. This physiological response helps the [[ventricle (heart)|ventricles]] compensate for increased resistance to blood ejection, ensuring stable [[stroke volume]] and [[cardiac output]] despite variations in [[aortic pressure]].
-This effect is found in denervated [[heart]] preparations, such as the '''Starling Preparation''', and as such, represents an intrinsic autoregulation mechanism.
+The effect was first described in 1912 by Russian physiologist '''[[Gleb von Anrep]]''', who experimentally demonstrated that increasing [[afterload]] results in a proportional and linear increase in [[ventricular]] contractility, independent of [[neural]] or [[hormonal]] influences. This phenomenon has since been recognized as an important component of [[cardiac autoregulation]].
-The Anrep effect is named after Russian physiologist Gleb von Anrep,<ref name="gleb">{{Cite journal | last1 = Gaddum | first1 = J. H. | doi = 10.1098/rsbm.1956.0002 | title = Gleb Anrep. 1891-1955 | journal = Biographical Memoirs of Fellows of the Royal Society | volume = 2 | pages = 19–42 | year = 1956 | jstor = 769473| pmid =  | pmc = }}</ref> who described it in 1912.
+== Mechanism ==
-Functionally, the Anrep effect allows the heart to compensate for an increased end-systolic volume present and the decreased stroke volume that occurs when aortic blood pressure 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.
+# '''Increased [[afterload]]:''' A sudden rise in [[aortic blood pressure]] leads to an increased '''end-systolic volume''' and reduced '''stroke volume''' due to the greater resistance encountered by the ventricles.
-Sustained myocardial stretch activates tension dependent Na<sup>+</sup>/H<sup>+</sup> exchangers, bringing Na<sup>+</sup> ions into the sarcolemma.
+This adaptation is particularly crucial for preventing circulation failure when '''systemic vascular resistance''' increases, such as during '''hypertension''' or '''exercise'''.
-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.<ref>{{Cite journal | last1 = Monroe | first1 = R. G. | doi = 10.1172/JCI107074 | title = The Anrep Effect Reconsidered | journal = The Journal of Clinical Investigation | volume = 51 | pages = 2573–2583 | year = 1972 | pmc = 332955 | pmid=5056656}}</ref>
+== Physiological Significance ==
-==References==
+Without the Anrep effect, an acute rise in '''aortic blood pressure''' would result in a '''persistent reduction in stroke volume''', compromising circulation and leading to inadequate '''tissue perfusion'''.
 {{reflist}}
 [[Category:Cardiology]]
+[[Category:Cardiac physiology]]
+[[Category:Circulatory system]]
 {{circulatory-stub}}

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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 [[Ventricle (heart)|ventricular]] inotropy.<ref>{{Cite journal | last1 = Von Anrep | first1 = G. | title = On the part played by the suprarenals in the normal vascular reactions of the body | journal = The Journal of Physiology | volume = 45 | issue = 5 | pages = 307–317 | year = 1912 | pmid = 16993158 | pmc = 1512890 | doi=10.1113/jphysiol.1912.sp001553}}</ref>

This effect is found in denervated [[heart]] preparations, such as the '''Starling Preparation''', and as such, represents an intrinsic autoregulation mechanism.

The Anrep effect is named after Russian physiologist Gleb von Anrep,<ref name="gleb">{{Cite journal | last1 = Gaddum | first1 = J. H. | doi = 10.1098/rsbm.1956.0002 | title = Gleb Anrep. 1891-1955 | journal = Biographical Memoirs of Fellows of the Royal Society | volume = 2 | pages = 19–42 | year = 1956 | jstor = 769473| pmid = | pmc = }}</ref> who described it in 1912.

Functionally, the Anrep effect allows the heart to compensate for an increased end-systolic volume present and the decreased stroke volume that occurs when aortic blood pressure 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.

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 uptaken by sarco/endoplasmic reticulum Ca2+-ATPase ([[SERCA]]) pumps.
Calcium induced calcium release (CICR) from the sarcoplasmic reticulum is increased upon stimulation of the cardiac myocyte by an action potential.
This leads to an increase in the force of contraction of the cardiac muscle to try and increase 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.<ref>{{Cite journal | last1 = Monroe | first1 = R. G. | doi = 10.1172/JCI107074 | title = The Anrep Effect Reconsidered | journal = The Journal of Clinical Investigation | volume = 51 | pages = 2573–2583 | year = 1972 | pmc = 332955 | pmid=5056656}}</ref>

==References==
{{reflist}}

[[Category:Cardiology]]

{{circulatory-stub}}

Anrep effect - Revision history

Prab at 05:11, 19 March 2025

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