The occurrence of cardiac muscle in the pulmonary veins of rodentia

Kramer, Aviv; Marks, L. S.

doi:10.1002/jmor.1051170202

Cited by 48 publications

(24 citation statements)

References 5 publications

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“…This tree subsequently enlarges in the following period to reach far into the smallest lung veins. 24 Taken together, between E10.5 and E12.5, a process of myocardium formation is observed around the pulmonary vein. Thereafter, this myocardial tree rapidly expands around the pulmonary vein branches.…”

Section: Development and Expression Analysis Of The Pulmonary Vein Mymentioning

confidence: 91%

Pitx2c and Nkx2-5 Are Required for the Formation and Identity of the Pulmonary Myocardium

Mommersteeg

Brown²,

Prall³

et al. 2007

Circulation Research

352

295

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Abstract-The pulmonary vein is sleeved by myocardium, which is a major source of atrial fibrillation and is involved in congenital sinus venosus defects. Little is known about the cellular origin and mechanism of formation of the pulmonary myocardium. We observed a biphasic process of pulmonary myocardium formation in mice. Firstly, a myocardial cell population forms de novo at the connection of the pulmonary vein and the atrium. Genetic labeling revealed that atrial cells do not contribute to this population, indicating it forms by differentiation of pulmonary mesenchymal cells. Secondly, these pulmonary myocardial cells initiate a phase of rapid proliferation and form the pulmonary myocardial sleeve. Pitx2c-deficient mice do not develop a pulmonary myocardial sleeve because they fail to form the initial pulmonary myocardial cells. Genetic-labeling analyses demonstrated that whereas the systemic venous return derives from Nkx2-5-negative precursors, the pulmonary myocardium derives from Nkx2-5-expressing precursors, indicating a distinct origin of the 2 venous systems. Nkx2-5 and its target gap-junction gene Cx40 are expressed in the atria and in the pulmonary myocardium but not in the systemic venous return, which expresses the essential pacemaker channel Hcn4. When Nkx2-5 protein level was lowered in a hypomorphic model, the pulmonary myocardium switched to a Cx40-negative, Hcn4-positive phenotype resembling that of the systemic venous return. In conclusion, our data suggest a cellular mechanism for pulmonary myocardium formation and highlight the key roles played by Pitx2c and Nkx2-5 in its formation and identity. Key Words: pulmonary myocardium Ⅲ pulmonary vein Ⅲ Nkx2-5 Ⅲ Pitx2c Ⅲ Hcn4 Ⅲ Cx40 Ⅲ differentiation Ⅲ lineage Ⅲ precursor T he pulmonary venous vessels are ensheathed by a myocardial layer known as the pulmonary myocardium. Besides its normal physiological functions, 1 the pulmonary myocardium is a major source of atrial fibrillation. 2 Several possible mechanisms for this pathology have been put forward, including intrinsic pacemaker activity and properties that facilitate reentrance. 3 A related issue, therefore, is whether the formed pulmonary myocardium shares both origin and phenotypic properties with nodal (pacemaker) tissues, 4 -7 such as the sinoatrial node and myocardium of the developing systemic venous return (sinus venosus/sinus horn), or with the atrial myocardium, which has a working myocardial phenotype much less prone to automaticity. The pulmonary myocardium is also involved in congenital cardiac malformations with anomalous connections to the atria or systemic venous return as major defects. 8 Although the morphology and physiology of the pulmonary myocardium have been extensively studied, little is known about the developmental origin and the molecular mechanisms controlling its formation and phenotype. The pulmonary myocardium has been proposed to form from atrial myocardium, which migrates around the pulmonary vein after its connection with the atrium has been established. 9,10...

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Section: Development and Expression Analysis Of The Pulmonary Vein Mymentioning

confidence: 91%

Pitx2c and Nkx2-5 Are Required for the Formation and Identity of the Pulmonary Myocardium

Mommersteeg

Brown²,

Prall³

et al. 2007

Circulation Research

352

295

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“…This tissue, named "pulmonary myocardium" (pm) by Favaro (Favaro, 1910), has been observed in numerous species including the shrew, mouse, rat, hamster, guinea pig, dog, deer, human, and bird (Kramer and Marks, 1965;Klika, 1976;Nathan and Gloobe, 1970;Endo et al, 1992a,b). Ultrastructural analyses showed that this muscle consists of striated mono-and bi-nucleate cells having narrow I-bands and intercalated discs and the sarcomere and single cell morphology are indistinguishable from cardiomyocytes (Karrer, 1959a,b;Ludatscher, 1968).…”

Section: Introductionmentioning

confidence: 99%

Murine pulmonary myocardium: Developmental analysis of cardiac gene expression

Jones

Sánchez

Robbins

1994

Developmental Dynamics

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Using ventricle-and atrial-specific riboprobes, we determined that the pulmonary myocardium exhibits an atrial pattern of cardiac-specific gene expression. Additionally, the developmental pattern of expression was studied using a riboprobe specific to the a-cardiac myosin heavy chain (a-MHC) gene transcript. We find that a-MHC gene expression is first detectable in the lung between 13.9-14.3 days post-coitum. Extension of the a-MHC specific hybridization signal into the pulmonary venous bed progresses through the neonatal period. The data are consistent with the hypothesis that the extension of a-MHC gene expression into the lung occurs via the migration of atrial myoblasts into the vein during atrial septation and remodeling of the sinus venosus and pulmonary venous trunk.

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“…Cardiac muscle in the walls of extraptilmonary veins of a variety of rodents was first recognized by Rattschel [1836], as cited by Benninghoff[ 1930], Reviews of early studies have been made by Benninghoffl 1930], and more recently by Karrer [1959], Kramer and Marks [1966] and De Almeida et at. [1975].…”

Section: Introductionmentioning

confidence: 99%

Electron-microscopic studies of the innervation of the pulmonary veins of the mouse

Hung¹,

Loosli²

1977

Cells Tissues Organs

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The innervation of the pulmonary veins was studied with electron microscopy. The adrenergic and cholinergic nerves were differentiated with potassium permanganate fixation. All three layers of the venous wall, namely, the tunica intima, media and adventitia, contained unmyelinated axons. Adrenergic and cholinergic axons were located near the cardiac muscle in the tunica media and near the smooth muscle in the tunica intima. The morphological relationships may explain the pharmacological and electrophysiological responses of the large pulmonary veins observed by others.

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The occurrence of cardiac muscle in the pulmonary veins of rodentia

Cited by 48 publications

References 5 publications

Pitx2c and Nkx2-5 Are Required for the Formation and Identity of the Pulmonary Myocardium

Pitx2c and Nkx2-5 Are Required for the Formation and Identity of the Pulmonary Myocardium

Murine pulmonary myocardium: Developmental analysis of cardiac gene expression

Electron-microscopic studies of the innervation of the pulmonary veins of the mouse

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