Comparison of Ca2+ release and uptake characteristics of the sarcoplasmic reticulum in isolated horse and rabbit cardiomyocytes.
Abstract: Both the cardiac action potential duration (APD) (0.6-1 s) and resting heart rate (30-40 beats/min) in the horse are significantly different from humans and smaller mammals, including the rabbit. This would be anticipated to have consequences for excitation-contraction (EC) coupling and require adaptation of the individual processes involved. The sarcoplasmic reticulum (SR) is one of the main components involved in EC coupling. This study examines and compares the activity of this organelle in the horse with that of the rabbit. In particular, the study focuses on SR Ca2+ release via the Ca2+ release channel/ryanodine receptor (RyR2) and Ca2+ uptake via the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) pump. Isolated cardiomyocytes from both horse and rabbit hearts were permeabilized, bathed in a mock intracellular solution, and exposed to a specified [Ca2+]. Rabbit cardiomyocytes exposed to 260 nM [Ca2+] produced spontaneous Ca2+ release and propagated Ca2+ waves. Horse cells failed to produce Ca2+ waves; instead, only local release in the form of Ca2+ sparks was evident. However, at 550 nM [Ca2+], Ca2+ waves were produced in both species. Ca2+ waves were four times less frequent yet approximately 1.5 times greater in amplitude in the horse compared with the rabbit. Ca2+ wave velocity was comparable between the species. The reason for this disparity in Ca2+ wave characteristics is unknown. Separate measurements of oxalate-supported Ca2+ uptake into the SR suggest that both horse and rabbit cardiomyocytes have comparable levels SERCA activity. The possible reasons for the observed differences in SR Ca2+ release between the horse and rabbit are discussed.
Publication Date: 2004-04-29 PubMed ID: 15117716DOI: 10.1152/ajpheart.00060.2004Google Scholar: Lookup
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- Comparative Study
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research paper investigates the activity of the sarcoplasmic reticulum, a crucial component in excitation-contraction coupling, in horse and rabbit heart cells. It specifically focuses on the release and uptake of calcium ions, uncovering differences between the species that suggest adaptations linked to their distinct heart rates and action potential durations.
Introduction and Objective
- The study was aimed at understanding the differences in the functioning of the sarcoplasmic reticulum (SR) in horses and rabbits, specifically focusing on Ca2+ release and uptake.
- SR plays a major role in excitation-contraction (EC) coupling in cardiac cells, a physiological process where an electrical signal is converted into a mechanical response. In this context, SR is responsible for releasing and absorbing Ca2+ ions for heart muscle contraction and relaxation.
Experimental Procedure
- Cardiomyocytes, or heart muscle cells, were isolated from the hearts of horses and rabbits.
- These isolated cells were permeabilized, bathed in a synthetic intracellular solution, and then exposed to specific concentrations of Ca2+.
- The researchers investigated how rabbit and horse cells reacted differently under equivalent conditions.
Results
- Rabbit cardiomyocytes exposed to 260 nM Ca2+ triggered spontaneous Ca2+ release and propagated Ca2+ waves, a normal part of the cardiac cycle.
- Horse cells did not produce Ca2+ waves at the same Ca2+ concentration; instead, they only displayed local release in the form of Ca2+ sparks.
- At a higher concentration, 550 nM Ca2+, horse and rabbit cells both produced Ca2+ waves. However, these waves were four times less frequent in horse cells, but 1.5 times greater in amplitude.
- Despite the differences in Ca2+ wave frequency and amplitude, the velocity of the Ca2+ waves was similar in both species.
Findings and Discussion
- The researchers observed that oxalate-supported Ca2+ uptake into the SR, suggesting that SERCA activity levels are comparable in both horse and rabbit cells.
- The discrepancy in Ca2+ wave characteristics remains unexplained, and the research offers some discussion on potential causes.
- This study raises further questions about the adaptation of EC coupling processes in different species according to their distinct rest heart rates and cardiac action potential durations.
Cite This Article
APA
Loughrey CM, Smith GL, MacEachern KE.
(2004).
Comparison of Ca2+ release and uptake characteristics of the sarcoplasmic reticulum in isolated horse and rabbit cardiomyocytes.
Am J Physiol Heart Circ Physiol, 287(3), H1149-H1159.
https://doi.org/10.1152/ajpheart.00060.2004 Publication
Researcher Affiliations
- Institute of Comparative Medicine, University of Glasgow Veterinary School, University of Glasgow, Glasgow G12 8QQ, UK.
MeSH Terms
- Animals
- Calcium / metabolism
- Cell Membrane Permeability
- Cell Size
- Heart / anatomy & histology
- Heart Ventricles
- Hemodynamics
- Horses / anatomy & histology
- Horses / metabolism
- Horses / physiology
- In Vitro Techniques
- Myocytes, Cardiac / cytology
- Myocytes, Cardiac / metabolism
- Rabbits / anatomy & histology
- Rabbits / metabolism
- Rabbits / physiology
- Sarcoplasmic Reticulum / metabolism
Citations
This article has been cited 9 times.- Shiels HA. Avian cardiomyocyte architecture and what it reveals about the evolution of the vertebrate heart.. Philos Trans R Soc Lond B Biol Sci 2022 Nov 21;377(1864):20210332.
- Sutanto H, van Sloun B, Schönleitner P, van Zandvoort MAMJ, Antoons G, Heijman J. The Subcellular Distribution of Ryanodine Receptors and L-Type Ca(2+) Channels Modulates Ca(2+)-Transient Properties and Spontaneous Ca(2+)-Release Events in Atrial Cardiomyocytes.. Front Physiol 2018;9:1108.
- McCarroll CS, He W, Foote K, Bradley A, Mcglynn K, Vidler F, Nixon C, Nather K, Fattah C, Riddell A, Bowman P, Elliott EB, Bell M, Hawksby C, MacKenzie SM, Morrison LJ, Terry A, Blyth K, Smith GL, McBride MW, Kubin T, Braun T, Nicklin SA, Cameron ER, Loughrey CM. Runx1 Deficiency Protects Against Adverse Cardiac Remodeling After Myocardial Infarction.. Circulation 2018 Jan 2;137(1):57-70.
- Elliott EB, McCarroll D, Hasumi H, Welsh CE, Panissidi AA, Jones NG, Rossor CL, Tait A, Smith GL, Mottram JC, Morrison LJ, Loughrey CM. Trypanosoma brucei cathepsin-L increases arrhythmogenic sarcoplasmic reticulum-mediated calcium release in rat cardiomyocytes.. Cardiovasc Res 2013 Nov 1;100(2):325-35.
- Richards MA, Clarke JD, Saravanan P, Voigt N, Dobrev D, Eisner DA, Trafford AW, Dibb KM. Transverse tubules are a common feature in large mammalian atrial myocytes including human.. Am J Physiol Heart Circ Physiol 2011 Nov;301(5):H1996-2005.
- Zhu LQ, Liu D, Hu J, Cheng J, Wang SH, Wang Q, Wang F, Chen JG, Wang JZ. GSK-3 beta inhibits presynaptic vesicle exocytosis by phosphorylating P/Q-type calcium channel and interrupting SNARE complex formation.. J Neurosci 2010 Mar 10;30(10):3624-33.
- Noszczyk-Nowak A, Nicpoń J, Nowak M, Slawuta P. Preliminary reference values for electrocardiography, echocardiography and myocardial morphometry in the European brown hare (Lepus europaeus).. Acta Vet Scand 2009 Jan 30;51(1):6.
- Rosati B, Dong M, Cheng L, Liou SR, Yan Q, Park JY, Shiang E, Sanguinetti M, Wang HS, McKinnon D. Evolution of ventricular myocyte electrophysiology.. Physiol Genomics 2008 Nov 12;35(3):262-72.
- Mascarello F, Sharova E, Patruno M, Maccatrozzo L, Damiani E, Sacchetto R. Proteins involved in calcium homeostasis expressed in horse cardiomyocytes.. Vet Res Commun 2008 Sep;32 Suppl 1:S159-62.
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