Bowditch effect
TheBowditch effect,also known as theTreppe phenomenonorTreppe effectorStaircase Phenomenon,[1][2]is anautoregulationmethod by which myocardialtensionincreases with an increase inheart rate.It was first observed byHenry Pickering Bowditchin 1871.
Mechanism
[edit]The underlying cause of the Bowditch effect is an increase in thecalciumconcentration in thesarcoplasmic reticulumofcardiac muscle cells,and its increased release intosarcoplasm.[3]
One of the explanations for an increase in the intracellular calcium concentration is the inability of theNa+/K+-ATPaseto keep up with influx ofsodiumat higherheart rates.When a higher heart rate occurs, for example due toadrenergic stimulation,theL-type calcium channelhas increased activity. Thesodium-calcium exchanger(which allows 3 Na+to flow down itselectrochemical gradientin exchange for 1 Ca++ion to flow out of the cell) works to decrease the levels of intracellular calcium. As the heart rate becomes more robust, and the length ofdiastoledecreases, the Na+/K+-ATPase, which removes the Na+brought into the cell by the Na+/Ca++exchanger, does not keep up with the rate of Na+influx. This leads to a less efficient Na+/Ca++exchange, since the gradient is decreasing for sodium and thedriving forcebehind calcium transport is actually theconcentration gradientof sodium, therefore Ca++builds up within the cell. This results in an accumulation of calcium in the myocardial cell via thesodium calcium exchangerand leads to a greater state ofinotropism,a mechanism which is also seen withcardiac glycosides.[4]
Alternatively, another mechanism is that the Na+-Ca++membrane exchanger, which operates continually, has less time to remove the Ca++that arrives in the cell.[5]This occurs because of the decreased length of diastole with positivechronotropy.[5]With an increased intracellular Ca++concentration, there follows a positiveinotropy.[5]
It has also been observed that increased heart rate stimulatesSERCA2a,which increases the calcium inflow and content in the sarcoplasmic reticulum. This activation of SERCA2a is indirectly by the phosphorylation ofphospholamban(PLN) by calmodulin kinase II (CAMK).[6]
Clinical significance
[edit]Positive Bowditch effect causes an increase incardiac outputdue to the increased force of contraction of heart muscles.[7]
This phenomenon is usually absent or even reversed (negative Bowditch effect) inheart failureand other diseases of heart, such ascardiomyopathyandcoronary artery disease.This is termed as the null or inverse staircase phenomenon.[7]The probable cause for this effect is attributed to mutations in SERCA2a.[8]
History
[edit]The Bowditch effect was first observed byHenry Pickering Bowditchin 1871, after whom it is named.[7][9]
References
[edit]- ^"Chapter 12".droualb.faculty.mjc.edu.Modesto Junior College.Archivedfrom the original on 2013-03-21.Retrieved28 December2020.
- ^Usman, Abira; Gandhi, Jason; Gupta, Gunjan (2024),"Physiology, Bowditch Effect",StatPearls,Treasure Island (FL): StatPearls Publishing,PMID30725706,retrieved2024-02-21
- ^Lewartowski, Bohdan; Pytkowski, Bohdan (1987). "Cellular mechanism of the relationship between myocardial force and frequency of contractions".Progress in Biophysics and Molecular Biology.50(2). Elsevier BV: 97–120.doi:10.1016/0079-6107(87)90005-8.ISSN0079-6107.
- ^Noble, M. I M (1988-08-01). "An introduction to modern work on the Bowditch phenomenon".Cardiovascular Research.22(8): 586–586.doi:10.1093/cvr/22.8.586.ISSN0008-6363.
- ^abcPhysiology at a Glance,Second Edition (2008) — Jeremy Ward & Roger Linden
- ^Boron, Walter; Boulpaep, Emile (2017).Medical Physiology.Philadelphia: Elsevier. p. 528.ISBN978-0-323-42796-8.
- ^abcUsman, Abira; Gupta, Gunjan (2020),"Physiology, Bowditch Effect",StatPearls,StatPearls Publishing,PMID30725706,retrieved2020-02-20
- ^Balcazar, Darío; Regge, Victoria; Santalla, Manuela; Meyer, Heiko; Paululat, Achim; Mattiazzi, Alicia; Ferrero, Paola (December 2018)."SERCA is critical to control the Bowditch effect in the heart".Scientific Reports.8(1): 12447.Bibcode:2018NatSR...812447B.doi:10.1038/s41598-018-30638-9.ISSN2045-2322.PMC6102201.PMID30127403.
- ^Ker, James (February 2009)."From Bowditch to beta-blockers: evolution of the understanding of the importance of heart rate and myocardial energetics in cardiomyopathy".Cardiovascular Journal of Africa.20(1): 37–38.ISSN1995-1892.PMC4200567.PMID19287814.