WordNet

of or relating to the myocardium
a plane figure with rounded sides curving inward at the top and intersecting at the bottom; conventionally used on playing cards and valentines; "he drew a heart and called it a valentine"
the courage to carry on; "he kept fighting on pure spunk"; "you havent got the heart for baseball" (同)mettle, nerve, spunk
an inclination or tendency of a certain kind; "he had a change of heart" (同)spirit
a playing card in the major suit that has one or more red hearts on it; "he led the queen of hearts"; "hearts were trumps"
the locus of feelings and intuitions; "in your heart you know it is true"; "her story would melt your bosom" (同)bosom
the hollow muscular organ located behind the sternum and between the lungs; its rhythmic contractions move the blood through the body; "he stood still, his heart thumping wildly" (同)pump, ticker
a firm rather dry variety meat (usually beef or veal); "a five-pound beef heart will serve six"
able to perceive sound
an opportunity to state your case and be heard; "they condemned him without a hearing"; "he saw that he had lost his audience" (同)audience
(law) a proceeding (usually by a court) where evidence is taken for the purpose of determining an issue of fact and reaching a decision based on that evidence
the ability to hear; the auditory faculty; "his hearing was impaired" (同)audition, auditory sense, sense of hearing, auditory modality
a session (of a committee or grand jury) in which witnesses are called and testimony is taken; "the investigative committee will hold hearings in Chicago"
receive a communication from someone; "We heard nothing from our son for five years"
examine or hear (evidence or a case) by judicial process; "The jury had heard all the evidence"; "The case will be tried in California" (同)try
perceive (sound) via the auditory sense
make ones way by force; "He muscled his way into the office"
animal tissue consisting predominantly of contractile cells (同)muscular_tissue
one of the contractile organs of the body (同)musculus
authority or power or force (especially when used in a coercive way); "the senators used their muscle to get the party leader to resign"
a form of whist in which players avoid winning tricks containing hearts or the queen of spades (同)Black_Maria

PrepTutorEJDIC

〈C〉『心臓』;胸 / 〈C〉(感情の中心をなす)『心』,気持ち / 〈U〉愛情,同情 / 〈U〉『勇気』,元気,熱意 / 《the ~》『中心』,内部,(物事の)本質,核心 / 〈C〉ハート形の物;(カードの)ハートの札
〈U〉『聴力』,聴覚〈U〉〈C〉(…を)『聞くこと』,(…の)聞き取り《+『of』+『名』》・〈C〉聞いてもらう機会,聞いてやること・聴取・聴聞会〈C〉(法廷などでの)尋問,審問,;(刑罰の減免を求める)釈明,意見陳述 / 〈U〉聞こえる距離(範囲)
〈音〉‘が'『聞こえる』,‘を'聞く(進行形にできない) / 〈人の言うこと〉‘に'『耳を傾ける』,‘を'注意深く聞く(listen);(裁判官などが)…の申し立てを聞く / 〈うわさ・ニュースなど〉‘を'『耳にしている』,聞いている / 『耳が聞こえる』 / 《しばしば命令形で》耳を傾ける,注意を向ける / 『うわさ』(『消息』)『を聞く』
〈U〉(動物体の組織としての)『筋肉』,筋(きん);〈C〉(体の各部を動かす)筋肉 / 〈U〉力,(特に)筋力,腕力 / 《俗に》(…に)強引に割り込む《+『in on』(『into, through』)+『名』》

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/05/29 16:10:31」(JST)

wiki en

An isolated cardiac muscle cell, beating

Cardiac muscle (heart muscle) is involuntary striated muscle that is found in the walls and histological foundation of the heart, specifically the myocardium. Cardiac muscle is one of three major types of muscle, the others being skeletal and smooth muscle. These three types of muscle all form in the process of myogenesis. The cells that constitute cardiac muscle, called cardiomyocytes or myocardiocytes, contain only one nucleus.^[1]^[2]^{[page needed]} The myocardium is the muscle tissue of the heart, and forms a thick middle layer between the outer epicardium layer and the inner endocardium layer.

Coordinated contractions of cardiac muscle cells in the heart propel blood out of the atria and ventricles to the blood vessels of the left/body/systemic and right/lungs/pulmonary circulatory systems. This complex mechanism illustrates systole of the heart.

Cardiac muscle cells, unlike most other tissues in the body, rely on an available blood and electrical supply to deliver oxygen and nutrients and remove waste products such as carbon dioxide. The coronary arteries help fulfill this function.

Structure

Intercalated discs are part of the cardiac muscle sarcolemma and they contain gap junctions and desmosomes.

3D rendering showing thick myocardium within heart wall.

Striation

Cardiac muscle exhibits cross striations formed by alternating segments of thick and thin protein filaments. Like skeletal muscle, the primary structural proteins of cardiac muscle are actin and myosin. The actin filaments are thin, causing the lighter appearance of the I bands in striated muscle, whereas the myosin filament is thicker, lending a darker appearance to the alternating A bands as observed with electron microscopy. However, in contrast to skeletal muscle, cardiac muscle cells may be branched instead of linear and longitudinal.

T-tubules

Another histological difference between cardiac muscle and skeletal muscle is that the T-tubules in the cardiac muscle are larger and broader and run along the Z-discs. There are fewer T-tubules in comparison with skeletal muscle. Also, cardiac muscle forms diads instead of the triads formed between the T-tubules and the sarcoplasmic reticulum in skeletal muscle. T-tubules play critical role in excitation-contraction coupling (ECC). Recently, the action potentials of T-tubules were recorded optically by Guixue Bu et al.^[3]

Intercalated discs

Intercalated discs are complex adhering structures that connect single cardiac myocytes to an electrochemical syncytium (in contrast to the skeletal muscle, which becomes a multicellular syncytium during mammalian embryonic development) and are responsible mainly for force transmission during muscle contraction. They also support the rapid spread of action potentials and the synchronized contraction of the myocardium. Intercalated discs are described to consist of three different types of cell-cell junctions: the actin filament anchoring adherens junctions (fascia adherens), the intermediate filament anchoring desmosomes (macula adherens), and gap junctions. Gap junctions are responsible for electrochemical and metabolic coupling. They allow action potentials to spread between cardiac cells by permitting the passage of ions between cells, producing depolarization of the heart muscle. However, novel molecular biological and comprehensive studies unequivocally showed that intercalated discs consist for the most part of mixed-type adhering junctions named area composita (pl. areae compositae) representing an amalgamation of typical desmosomal and fascia adhaerens proteins (in contrast to various epithelia).^[4]^[5]^[6] The authors discuss the high importance of these findings for the understanding of inherited cardiomyopathies (such as arrhythmogenic right ventricular cardiomyopathy).

Under light microscopy, intercalated discs appear as thin, typically dark-staining lines dividing adjacent cardiac muscle cells. The intercalated discs run perpendicular to the direction of muscle fibers. Under electron microscopy, an intercalated disc's path appears more complex. At low magnification, this may appear as a convoluted electron dense structure overlying the location of the obscured Z-line. At high magnification, the intercalated disc's path appears even more convoluted, with both longitudinal and transverse areas appearing in longitudinal section.^[7]

Physiology

In contrast to skeletal muscle, cardiac muscle requires extracellular calcium ions for contraction to occur. Like skeletal muscle, the initiation and upshoot of the action potential in ventricular muscle cells is derived from the entry of sodium ions across the sarcolemma in a regenerative process. However, an inward flux of extracellular calcium ions through L-type calcium channels sustains the depolarization of cardiac muscle cells for a longer duration. The reason for the calcium dependence is due to the mechanism of calcium-induced calcium release (CICR) from the sarcoplasmic reticulum that must occur under normal excitation-contraction (EC) coupling to cause contraction. Once the intracellular concentration of calcium increases, calcium ions bind to the protein troponin, which initiate extracellular fluid and intracellular stores, and skeletal muscle, which is only activated by calcium stored in the sarcoplasmic reticulum.

Regeneration of heart muscle cells

Dog cardiac muscle (400X)

Until recently, it was commonly believed that cardiac muscle cells could not be regenerated. However, a study reported in the April 3, 2009 issue of Science contradicts that belief.^[8] Olaf Bergmann and his colleagues at the Karolinska Institute in Stockholm tested samples of heart muscle from people born before 1955 had very little cardiac muscle around their heart, many showing with disabilities from this abnormality. By using DNA samples from many hearts, the researchers estimated that a 20-year-old renews about 1% of heart muscle cells per year, and about 45 percent of the heart muscle cells of a 50-year-old were generated after he or she was born.

One way that cardiomyocyte regeneration occurs is through the division of pre-existing cardiomyocytes during the normal ageing process.^[9] The division process of pre-existing cardiomyocytes has also been shown to increase in areas adjacent to sites of myocardial injury. In addition, certain growth factors promote the self-renewal of endogenous cardiomyocytes and cardiac stem cells. For example, insulin-like growth factor 1, hepatocyte growth factor, and high-mobility group protein B1 increase cardiac stem cell migration to the affected area, as well as the proliferation and survival of these cells.^[10] Some members of the fibroblast growth factor family also induce cell-cycle re-entry of small cardiomyocytes. Vascular endothelial growth factor also plays an important role in the recruitment of native cardiac cells to an infarct site in addition to its angiogenic effect.

Based on the natural role of stem cells in cardiomyocyte regeneration, researchers and clinicians are increasingly interested in using these cells to induce regeneration of damaged tissue. Various stem cell lineages have been shown to be able to differentiate into cardiomyocytes, including bone marrow stem cells. For example, in one study, researchers transplanted bone marrow cells, which included a population of stem cells, adjacent to an infarct site in a mouse model. Nine days after surgery, the researchers found a new band of regenerating myocardium.^[11] However, this regeneration was not observed when the injected population of cells was devoid of stem cells, which strongly suggests that it was the stem cell population that contributed to the myocardium regeneration. Other clinical trials have shown that autologous bone marrow cell transplants delivered via the infarct-related artery decreases the infarct area compared to patients not given the cell therapy.^[12]

Clinical significance

Occlusion (blockage) of the coronary arteries by atherosclerosis and/or thrombosis can lead to myocardial infarction (heart attack), where part of the myocardium is injured due to ischemia (not receiving enough oxygen). Certain viruses lead to myocarditis (inflammation of the myocardium). Cardiomyopathies are inherent diseases of the myocardium, many of which are caused by genetic mutations.

References

^ Olivetti G, Cigola E, Maestri R, et al. (July 1996). "Aging, cardiac hypertrophy and ischemic cardiomyopathy do not affect the proportion of mononucleated and multinucleated myocytes in the human heart". Journal of Molecular and Cellular Cardiology 28 (7): 1463–77. doi:10.1006/jmcc.1996.0137. PMID 8841934.
^ Pollard, Thomas D. and Earnshaw, William. C., "Cell Biology". Philadelphia: Saunders. 2007.
^ Bu G, Adams H, Berbari EJ, Rubart M (March 2009). "Uniform action potential repolarization within the sarcolemma of in situ ventricular cardiomyocytes". Biophys. J. 96 (6): 2532–46. doi:10.1016/j.bpj.2008.12.3896. PMC 2907679. PMID 19289075.
^ Franke WW, Borrmann CM, Grund C, Pieperhoff S (February 2006). "The area composita of adhering junctions connecting heart muscle cells of vertebrates. I. Molecular definition in intercalated disks of cardiomyocytes by immunoelectron microscopy of desmosomal proteins". Eur. J. Cell Biol. 85 (2): 69–82. doi:10.1016/j.ejcb.2005.11.003. PMID 16406610.
^ Goossens S, Janssens B, Bonné S, et al. (June 2007). "A unique and specific interaction between alphaT-catenin and plakophilin-2 in the area composita, the mixed-type junctional structure of cardiac intercalated discs". J. Cell. Sci. 120 (Pt 12): 2126–36. doi:10.1242/jcs.004713. PMID 17535849.
^ Pieperhoff S, Barth M, Rickelt S, Franke WW (2010). Desmosomal molecules in and out of adhering junctions: normal and diseased states of epidermal, cardiac and mesenchymally derived cells. In Mahoney MG, Müller EJ, Koch PJ. "Desmosomes and desmosomal cadherin function in skin and heart diseases-advancements in basic and clinical research". Dermatol Res Pract 2010: 1. doi:10.1155/2010/725647. PMC 2946574. PMID 20885972.
^ Histology image:22501loa from Vaughan, Deborah (2002). A Learning System in Histology: CD-ROM and Guide. Oxford University Press. ISBN 978-0195151732.
^ Bergmann O, Bhardwaj RD, Bernard S, et al. (April 2009). "Evidence for cardiomyocyte renewal in humans". Science 324 (5923): 98–102. doi:10.1126/science.1164680. PMC 2991140. PMID 19342590.
^ Senyo SE, Steinhauser ML, Pizzimenti CL, Yang VK, Cai L, Wang M, Wu TD, Guerguin-Kern JL, Lechene CP, Lee RT (January 2013). "Mammalian heart renewal by pre-existing cardiomyocytes". Nature 493 (7432): 433–6. doi:10.1038/nature11682. PMC 3548046. PMID 23222518.
^ Germani A, Di Rocco G, Limana F, Martelli F, Capogrossi MC (March 2007). "Molecular mechanisms of cardiomyocyte regenerate and therapeutic outlook". Trends Mol Med 13 (3): 125–33. doi:10.1016/j.molmed.2007.01.002. PMID 17257896.
^ Orlic D, Kajstura J, Chimenti S, Jakoniuk I, Anderson SM, Li B, Pickel K, McKay R, Nadal-Ginard B, Bodine DM, Anversa P (April 2001). "Bone marrow cells regenerate infarcted myocardium". Nature 410 (6829): 701–5. doi:10.1038/35070587. PMID 11287958.
^ Orlic D, Hill JM, Arai AE (December 2002). "Stem cells for myocardial regeneration". Circ Res 91 (12): 1092–102. doi:10.1161/01.RES.0000046045.00846.B0. PMID 12480809.

UpToDate Contents

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1. 心不全における骨格筋機能低下および運動耐容能低下 skeletal muscle dysfunction and exercise intolerance in heart failure
2. 心不全および心筋症における心突然死の二次予防 secondary prevention of sudden cardiac death in heart failure and cardiomyopathy
3. 呼吸筋力検査 tests of respiratory muscle strength
4. 心不全または心筋症患者の病因及び重症度の決定 determining the etiology and severity of heart failure or cardiomyopathy
5. 心不全に対する試験中および新規の治療 investigational and emerging therapies for heart failure

English Journal

l-dehydroascorbic acid can substitute l-ascorbic acid as dietary vitamin C source in guinea pigs.

Frikke-Schmidt H1, Tveden-Nyborg P1, Lykkesfeldt J2.
Redox biology.Redox Biol.2016 Apr;7:8-13. doi: 10.1016/j.redox.2015.11.003. Epub 2015 Nov 21.
Vitamin C deficiency globally affects several hundred million people and has been associated with increased morbidity and mortality in numerous studies. In this study, bioavailability of the oxidized form of vitamin C (l-dehydroascorbic acid or DHA)-commonly found in vitamin C containing food produc
PMID 26609560

Molecular characterization and expression patterns of emerin (EMD) gene in skeletal muscle between Meishan and Large White pigs.

Wang Y1, Xiao X2, Wang L3.
Gene.Gene.2016 Mar 15;579(1):41-6. doi: 10.1016/j.gene.2015.12.059. Epub 2015 Dec 29.
The emerin protein is a nuclear membrane protein and has important functions in muscle development, regeneration, and cell signal transduction. However, knowledge regarding emerin in the domestic animal is limited. In this study, we cloned and characterized the pig emerin (EMD) gene. Semi-quantitati
PMID 26743124

Analysis of the zebrafish sox9b promoter: Identification of elements that recapitulate organ-specific expression of sox9b.

Burns FR1, Lanham KA2, Xiong KM3, Gooding AJ4, Peterson RE2, Heideman W2.
Gene.Gene.2016 Mar 10;578(2):281-9. doi: 10.1016/j.gene.2015.12.041. Epub 2015 Dec 23.
The SRY-related high-mobility box 9 (SOX9) gene is expressed in many different tissues. To better understand the DNA elements that control tissue-specific expression, we cloned and sequenced a 2.5kb fragment lying 5' to the zebrafish sox9b gene transcriptional start site. Three regions of this clone
PMID 26721460

Japanese Journal

尿中成長ホルモンを指標とした運動評価法の検討

秋山真敏/吉村英悟/米内奈美/橋田誠一
徳島文理大学研究紀要 85, 57-66, 2013-03-00
… Background: An increase in muscle quantity and a gain in performance are generally used as indices in the assessment of exercise effect. … In addition, exercise at 70% Heart Rate Reserve (HRR) intensity resulted in the greatest secretion of growth hormone (p <0.01). … Future studies will examine the effect of food intake before and after exercise in the evening on muscle growth. …
NAID 110009573837

拡張型心筋症に対する自己心温存手術 : 術式の変遷,遠隔期成績,予後規定因子 (特集重症心不全に対する外科治療)

星野丈二,深田靖久,廣田真規 [他]
胸部外科 66(1), 31-36, 2013-01-00
NAID 40019541702

Green Tea Catechins Increase the Force of Contraction in Isolated Guinea Pig Atrial Muscle Preparations by Increasing the Amplitude of Intracellular Ca?? Concentration

SASAKI Takushi,KAMATA Ryo,UENO Shunji [他]
The journal of veterinary medical science 74(12), 1603-1608, 2012-12-00
NAID 40019543993

Related Pictures

★リンクテーブル★

リンク元	「心筋」「myocardial」「myocardia」
拡張検索	「heart muscle cell」
関連記事	「hearing」「hear」「heart」「muscle」

「心筋」

Cardiac muscle
	Cardiac muscle
	Cardiac muscle tissue is only found in the heart
Latin	Textus muscularis striatus cardiacus
Code	TH H2.00.05.2.02001

　　[★]

英: cardiac muscle (K), heart muscle, myocard cardiac muscle, myocardium
関: 心筋の活動電位、横紋筋、筋肉

骨格筋との違い

筋小胞体が発達していない

心筋の酸素消費量 (SPC.226)

心筋の酸素消費量の指標(doble product)＝心拍数×収縮期血圧

(tension-time index)=左心室内圧曲線収縮期相の面積(mmHg/s)×心拍数

(doble product)∝(tension-time index)

心筋の筋収縮

1. 骨格筋細胞と違い心筋細胞は介在板を有しており、介在板近傍に存在するギャップ結合によって活動電位が伝播する。
2. ギャップジャンクションを通じて活動電位が伝播すると、心筋細胞膜上の電位依存性Na+チャネルが開き、脱分極が筋細胞全体に広がる。
3. 脱分極はT細管（横行管）に伝わり、T細管に存在する電位依存性のタンパク質の構造を変化させ、筋小胞体上のCa2+放出チャネルを開く。
4. さらに少し遅れてCa2+/Na+チャネルが長時間開口し、細胞内に多量のCa2+/Na+を取り込む。
5. 心筋細胞のT細管は細胞外部に開口しており、Ca2+の取り込みが容易になっている。
6. このようにして、細胞外と筋小胞体中のCa2+が細胞質に拡散する。
7. ここで、筋収縮に関わるアクチンフィラメントにトロポミオシンとトロポニンが結合し、収縮開始を妨げているが、Ca2+がトロポニンに結合すると、トロポミオシンがアクチンフィラメント上で場所を変える。
8. この結果、トロポミオシンが覆い隠していたアクチンフィラメントのミオシン結合部位が露出する。
9. ミオシンはATPの加水分解のエネルギーを使って、アクチンフィラメントに結合できる構造をとり、アクチンに結合する。
10. ミオシンがアクチンフィラメントで首振り運動をすることで筋収縮が起こる。

Henry Gray (1825-1861). Anatomy of the Human Body. 1918.