Cardiac Corpuscles: A "New" Morphofunctional Entity? / Corpúsculos Cardíacos: ¿Una "Nueva" Entidad Morfofuncional?

SUMMARY: The existence of "transitional muscular structures" between subendocardial branches (Purkinje fibers) and ventricular working muscle fibers (WF) was first described by the German anatomist, Kurt Goerttler, in 1964. He designated them as "subendocardial nucleus organs." He supposed such fibers functioned as mechanoreceptors, controlling of the intensity of contraction of the ventricular musculature. Brazilian anatomist Ferraz de Carvalho described similar structures in 1993. A thorough literature search failed to identify any other research articles confirming or denying their existence. The objective of this work was to find such structures in subendocardial ventricular walls in human hearts. We collected fifteen formalin-preserved hearts from the Anatomy Department of São Paulo University and sectioned the apical portions on the right and left ventricles according to method used by Goerttler. We utilized conventional histology (light microscopy- LM), scanning electron microscopy (SEM), and a new preservation method called micro- plastination (MP). At the anterior wall of the right ventricle in the subendocardial region between the interventricular septum and moderator band, we found several bundles of fusiform and helicoidal fibers of similar histology to the WF. The bundles measured between 400 and 1150 µm in length and were separated from adjacent muscular fibers by thin collagen fiber, thus acting as a "pseudo capsule." Some structures seemed to be linked to PF and were appeared to be lymphatic and blood vessels and nerves. We called those structures "cardiac corpuscles" (CC). The observation of the previously "unknown" CC in this initial study confirmed the previous descriptions and its discovery may contribute to new perspectives in the study of cardiac muscle structure and function.

La existencia de "estructuras musculares de transición" entre los ramos subendocárdicos (fibras de Purkinje) y las fibras musculares ventriculares activas(FMV) fue descrita por primera vez por el anatomista alemán Kurt Goerttler en 1964, quien las denominó "órganos del núcleo subendocárdico". Supuso que tales fibras funcionaban como mecanoreceptores, controlando la intensidad de la contracción de la musculatura ventricular. El anatomista brasileño Ferraz de Carvalho describió estructuras similares en 1993. Una búsqueda bibliográfica exhaustiva no logró identificar ningún otro artículo de investigación que confirmara o negara su existencia. El objetivo de este trabajo fue encontrar dichas estructuras en las paredes ventriculares subendocárdicas de corazones humanos. Recolectamos 15 corazones conservados en formalina del Departamento de Anatomía de la Universidad de São Paulo y seccionamos las porciones apicales de los ventrículos derecho e izquierdo según el método utilizado por Goerttler. Utilizamos histología convencional (microscopía de luz-LM), microscopía electrónica de barrido (SEM) y un nuevo método de conservación llamado microplastinación (MP). En la pared anterior del ventrículo derecho en la región subendocárdica entre el tabique interventricular y la banda moderadora, encontramos varios haces de fibras fusiformes y helicoidales de histología similar a la FMV. Los haces medían entre 400 y 1150 µm de longitud y estaban separados de las fibras musculares adyacentes por una fina fibra de colágeno, actuando así como una "pseudocápsula". Algunas estructuras parecían estar vinculadas a la fibras de purkinje y parecían ser vasos linfáticos, sanguíneos y nerviosos. Llamamos a esas estructuras "corpúsculos cardíacos" (CC). La observación del CC previamente "desconocido" en este estudio inicial confirmó las descripciones anteriores y su descubrimiento puede contribuir a nuevas perspectivas en el estudio de la estructura y función del músculo cardíaco.

Structural distribution and mechanism of elastic fibers and collagen fibers in ventricular interstitium of aged rats / 解剖学报

Objective To investigate the structural distribution features and mechanism of elastic fibers and collagen fibers in ventricular interstitium of aged rats. Methods Five young SD rats (24 weeks) and five old SD rats (104 weeks) were used,and their cardiac function was examined by echocardiography. Modified Weigert elastic fiber staining, immunohistochemistry, immunofluorescence and Western blotting techniques were used to detect the expression changes of type I and IH collagen fibers and their proteins, elastic fibers and their proteins, matrix metalloproteinase 2 (MMP-2), matrix metalloproteinase 9 (MMP-9) and tissue inhibitor of metalloproteinase 2 (TIMP-2), respectively. Results The type I and type IH collagen in the ventricular interstitium of aged rats was very sufficient and wrapped around the cardiomyocytes. Compared with the young rats, the content of collagen protein in the ventricular interstitium of the aged rats significantly increased (P<0. 05). Elastic fibers in the ventricular interstitium of the aged rats were and widely distributed. Compared with the young rats, the number of elastic fibers and the level of elastin in the ventricular interstitium of the aged rats significantly decreased (P<0. 05), and the expression levels of MMP-2 and MMP-9 in ventricular muscle of aged rats increased, and the)' were correlated with the level of elastin. The level of TIMP-2 in ventricular muscle of aged rats decreased with age. Conclusion The number of collagen fibers and elastic fibers in ventricular interstitium of aged rats is fluctuated with each other. With the increase of age, the contents of TIMP-2 and elastic fibers in the ventricular interstitium gradually decreased, and the ratio of collagen fibers to elastic fibers is out of balance.

Cardiomyocyte-like differentiation of bone marrow mesenchymal stem cells induced by myocardial tissue lysates from different parts of the myocardium / 中国组织工程研究

BACKGROUND: Bone marrow mesenchymal stem cells can be induced into myocardial tissue-like structure in vitro. Myocardial tissue lysates from different parts of the myocardium can be used to construct differential microenvironments. Few studies have investigated the targeted induction efficiency of bone marrow mesenchymal stem cells and the expression of related genes. OBJECTIVE: To investigate the effects of lysates from different parts of the myocardium on the differentiation of bone marrow mesenchymal stem cells into myocardial tissue-like structures and to assess the correlation between the expressions of related genes during induction and myocardial tissue engineering. METHODS: Passage 3 bone marrow mesenchymal stem cells from Sprague-Dawley rats were cultured. Whole heart tissue lysate, atrial muscle tissue lysate, and ventricular muscle tissue lysate were used to construct different microenvironments to induce bone marrow mesenchymal stem cells to differentiate into cardiomyocyte-like cells. The morphological changes and ultrastructure of cells were observed with an inverted phase contrast microscope and transmission electron microscopy. Expression of α-actin and cTnI was detected by immunofluorescence staining. qRT-PCR was used to detect the expression of upstream molecules ANP, HCN4 and downstream molecules MLC-2v in the cAMP/PKA signaling pathway after induction. RESULTS AND CONCLUSION: (1) Each induction cell group followed similar morphological changes: Cardiomyocyte-like cells were capable of autonomic beats, rhythmic contractions and relaxations; under the transmission electron microscope, there were a large number of arranged myofilaments; immunofluorescent staining showed positive expression of α-actin and cTnI. (2) The whole heart tissue lysate was able to induce the differentiation of bone marrow mesenchymal stem cells into rice grain-sized myocardial tissue-like structures with collagen fibers. (3) Atrial muscle tissue lysate could induce bone marrow mesenchymal stem cells to differentiate into atrial muscle-like cells. Autonomic beats appeared earlier, but the beat frequency and duration were shorter. ANP and HCN4 were highly expressed in atrial myocytes. (4) Ventricular muscle tissue lysate induced bone marrow mesenchymal stem cells to differentiate into ventricular muscle-like cells with no secretory granules, and MLC-2v was highly expressed in ventricular muscle-like cells. (5) To conclude, the whole heart tissue lysate can induce bone marrow mesenchymal stem cells to form myocardial tissue-like structures. Atrial muscle tissue lysate can induce bone marrow mesenchymal stem cells to differentiate into atrial muscle-like cells. Ventricular muscle tissue lysate can induce bone marrow mesenchymal stem cells to differentiate into ventricular muscle-like cells. By constructing a specific microenvironment, bone marrow mesenchymal stem cells can be differentiated to cardiomyocytes in different parts, providing laboratory data for the construction of myocardial tissue engineering.

Left Ventricular Anomalous Muscle Band and Electrocardiographic Repolarization Changes in a 5 Year Old Girl

We report here on a previously healthy 5-year-old girl with significant electrocardiographic repolarization abnormalities and a left ventricular mass. After the clinical evaluation, a large muscular false tendon was found within the left ventricular cavity.

Effects of Picrotoxin on the Rate, Contractility and Action Potential of Isolated Frog Heart / 第三军医大学学报

Picrotoxin is an anatagninst of gamma-aminobutyric acid, which is an internal inhibition-transmitter in the central nervous system, Picrotoxin exerts a biphasic action on the blood pressure and heart rate in rats and cats in vivo. That is to say, in the initial stage, picrotoxin can lower the blood pressure and heart rate, and then an elevation of these two even above the original level can be observed, up to the present, from the authors limited literature, there has been no report dealing with the problem whether picrotoxin can act on an isolated heart directly.In this study, the heart of a frog was isolated and routine intubation of the heart was done for its perfusion. Physiological polyconduction instrument was inserted through a mechanical transducer to record the heart rale and myocardial contractility. A suspending glass microelectrode coupling with a microamplifier is used to record the action potential of the ventricular myocardium. Real time analysis of all the data was accomplished with a microcomputer. The dosages of picrotoxin used were 1,5, 3.0, 6.0, and 12.0 mg per kilogram of body weight.It was found that picrotcxin can directly act on the isolated frog heart. The results were as follows.1 ) Picrotoxin exerts inhibition on the special conduction system of the heart,and the A-V node and venous sinus are very sensitive. Complete or partial transmission block can be induced.2 ) It can elicit clearly a fall of the heart rate but no biphasic action can berevealed. 3) It can reduce the myocardial contractility, suggesting that the calciuminflow during the functioning period of the action potential is effected. 4 ) It can reduce the amplitude of the action potential but no effect on themaximal depolarization speed is observed, suggesting that picrotoxin islikely to affect the level of resting potential but not the action potentialin the depolarized period.