That the highly trabeculated ventricular walls of the developing embryos transform to the arrangement during the fetal stages, when the mural architecture is dominated by the thickness of the compact myocardium, has been explained by the coalescence of trabeculations, often erroneously described as 'compaction'. Recent data, however, support differential rates of growth of the trabecular and compact layers as the major driver of change. Here, these processes were assessed quantitatively and visualized in standardized views. We used a larger dataset than has previously been available of mouse hearts, covering the period from embryonic day 10.5 to postnatal day 3, supported by images from human hearts. The volume of the trabecular layer increased throughout development, in contrast to what would be expected had there been 'compaction'. During the transition from embryonic to fetal life, the rapid growth of the compact layer diminished the proportion of trabeculations. Similarly, great expansion of the central cavity reduced the proportion of the total cavity made up of intertrabecular recesses. Illustrations of the hearts with the median value of left ventricular trabeculation confirm a pronounced growth of the compact wall, with prominence of the central cavity. This corresponds, in morphological terms, to a reduction in the extent of the trabecular layer. Similar observations were made in the human hearts. We conclude that it is a period of comparatively slow growth of the trabecular layer, rather than so-called compaction, that is the major determinant of the changing morphology of the ventricular walls of both mouse and human hearts.

• Klíčová slova
• cardiac morphogenesis, compaction, excessive trabeculation, heart development, ventricular trabeculation,
• MeSH
• gestační stáří MeSH
• lidé MeSH
• myši MeSH
• srdeční komory * anatomie a histologie   embryologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The mammalian ventricular myocardium forms a functional syncytium due to flow of electrical current mediated in part by gap junctions localized within intercalated disks. The connexin (Cx) subunit of gap junctions have direct and indirect roles in conduction of electrical impulse from the cardiac pacemaker via the cardiac conduction system (CCS) to working myocytes. Cx43 is the dominant isoform in these channels. We have studied the distribution of Cx43 junctions between the CCS and working myocytes in a transgenic mouse model, which had the His-Purkinje portion of the CCS labeled with green fluorescence protein. The highest number of such connections was found in a region about one-third of ventricular length above the apex, and it correlated with the peak proportion of Purkinje fibers (PFs) to the ventricular myocardium. At this location, on the septal surface of the left ventricle, the insulated left bundle branch split into the uninsulated network of PFs that continued to the free wall anteriorly and posteriorly. The second peak of PF abundance was present in the ventricular apex. Epicardial activation maps correspondingly placed the site of the first activation in the apical region, while some hearts presented more highly located breakthrough sites. Taken together, these results increase our understanding of the physiological pattern of ventricular activation and its morphological underpinning through detailed CCS anatomy and distribution of its gap junctional coupling to the working myocardium.

• Klíčová slova
• cardiac conduction system, connexin, immunohistochemistry, myocardium, optical mapping,
• MeSH
• konexin 43 fyziologie   MeSH
• mezerový spoj fyziologie   MeSH
• mezibuněčná komunikace * MeSH
• myši MeSH
• perikard cytologie   fyziologie   MeSH
• Purkyňova vlákna cytologie   fyziologie   MeSH
• srdeční komory patologie   MeSH
• svalové buňky cytologie   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• GJA1 protein, mouse MeSH Prohlížeč
• konexin 43 MeSH

The heart is characterized by a remarkable degree of heterogeneity. Since different cardiac pathologies affect different cardiac regions, it is important to understand molecular mechanisms by which these parts respond to pathological stimuli. In addition to already described left ventricular (LV)/right ventricular (RV) and transmural differences, possible baso-apical heterogeneity has to be taken into consideration. The aim of our study has been, therefore, to compare proteomes in the apical and basal parts of the rat RV and LV. Two-dimensional electrophoresis was used for the proteomic analysis. The major result of this study has revealed for the first time significant baso-apical differences in concentration of several proteins, both in the LV and RV. As far as the LV is concerned, five proteins had higher concentration in the apical compared to basal part of the ventricle. Three of them are mitochondrial and belong to the "metabolism and energy pathways" (myofibrillar creatine kinase M-type, L-lactate dehydrogenase, dihydrolipoamide dehydrogenase). Myosin light chain 3 is a contractile protein and HSP60 belongs to heat shock proteins. In the RV, higher concentration in the apical part was observed in two mitochondrial proteins (creatine kinase S-type and proton pumping NADH:ubiquinone oxidoreductase). The described changes were more pronounced in the LV, which is subjected to higher workload. However, in both chambers was the concentration of proteins markedly higher in the apical than that in basal part, which corresponds to the higher energetic demand and contractile activity of these segments of both ventricles.

• Klíčová slova
• Heart, Myocardial heterogeneity, Proteomics, Two-dimensional electrophoresis, Ventricle, Ventricular myocardium,
• MeSH
• 2D gelová elektroforéza MeSH
• chaperon hsp60 metabolismus   MeSH
• chromatografie kapalinová MeSH
• dihydrolipoamiddehydrogenasa metabolismus   MeSH
• energetický metabolismus MeSH
• kreatinkinasa, forma MM metabolismus   MeSH
• L-laktátdehydrogenasa metabolismus   MeSH
• lehké řetězce myosinu metabolismus   MeSH
• mitochondriální proteiny metabolismus   MeSH
• potkani Wistar MeSH
• proteomika * MeSH
• respirační komplex I metabolismus   MeSH
• srdeční komory enzymologie   metabolismus   MeSH
• svalové proteiny izolace a purifikace   metabolismus   MeSH
• tandemová hmotnostní spektrometrie MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chaperon hsp60 MeSH
• dihydrolipoamiddehydrogenasa MeSH
• Hspd1 protein, rat MeSH Prohlížeč
• kreatinkinasa, forma MM MeSH
• L-laktátdehydrogenasa MeSH
• lehké řetězce myosinu MeSH
• mitochondriální proteiny MeSH
• respirační komplex I MeSH
• svalové proteiny MeSH