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Glycogen and the propensity for atrial fibrillation: intrinsic anatomic differences in glycogen in the left and right atria in the goat heart.

Embi AA, Scherlag BJ, Ritchey JW - N Am J Med Sci (2014)

Bottom Line: Previous experimental studies have demonstrated electrophysiological and structural remodeling in pacing induced atrial fibrillation.We are reporting for the first time that the right atrial appendage showed scattered glycogen granules throughout the atrial myocytes which delineated the intercalated discs; whereas glycogen in the left atrial appendage was more dense within cells and coalesced against the intercalated discs and side to side junctions between myocytes.We show that glycogen is heterogeneously distributed in both atria in the normal goat heart; however, the density of glycogen deposits concentrating against the intercalated discs and side to side connections in the left atrial appendage is a critically distinct difference.

View Article: PubMed Central - PubMed

Affiliation: Independent, Miami, Florida, USA.

ABSTRACT

Background: Previous experimental studies have demonstrated electrophysiological and structural remodeling in pacing induced atrial fibrillation. The latter has been characterized by glycogen accumulation but no connection to atrial fibrillation induction and maintenance has as yet been proposed.

Aims: We determined the presence of glycogen in the right and left atrial appendages in the goat heart, in order to find any intrinsic disparity in distribution and concentration between these sites.

Materials and methods: Atrial appendages from 5 goats were stained by the Periodic acid Schiffmethod to determine the presence of glycogen and the concentration of glycogen by morphometric analysis.

Results: We are reporting for the first time that the right atrial appendage showed scattered glycogen granules throughout the atrial myocytes which delineated the intercalated discs; whereas glycogen in the left atrial appendage was more dense within cells and coalesced against the intercalated discs and side to side junctions between myocytes. Also, morphometric analysis determined that the stained regions of the right atrial appendages averaged, 0.8 ± 1.3 μm(2) compared to the left atrial appendage sections, 2.6 ± 3 μm(2), P = 0.02. We show that glycogen is heterogeneously distributed in both atria in the normal goat heart; however, the density of glycogen deposits concentrating against the intercalated discs and side to side connections in the left atrial appendage is a critically distinct difference. Impediment of cell to cell conduction could result in a non-uniform wavefront of activation, with areas of slowed conduction, predisposing the left atrium to reentrant based atrial fibrillation.

Conclusion: These findings provide a basis for the well-known greater propensity for atrial fibrillation in the left versus the right atrium.

No MeSH data available.


Related in: MedlinePlus

RAAs myocardium showing PAS staining (never as conspicuous as the LAA) Bar 1 mm. Please note that there is subepicardial glycogen concentration
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Figure 4: RAAs myocardium showing PAS staining (never as conspicuous as the LAA) Bar 1 mm. Please note that there is subepicardial glycogen concentration

Mentions: The present study demonstrates that in the normal caprine heart there are intrinsic quantitative differences in glycogen concentrations between the LAA and RAA. Both sides showed subepicardial presence of glycogen [Figures 4 and 5] that is notably displayed in a greater concentration in the LAA. The significantly greater glycogen in the LAA is heterogeneously found as high-density depositions against the intercalated discs and extending into the myocytes. Also condensed glycogen was observed at the sided to side junction of adjacent myocytes. In the RAA granules of glycogen were scattered throughout the cells. Although there were individual myocytes in which the glycogen granules outlined the intercalated disc and side to side myocyte junctions, many other cells did not show this pattern [Figure 1, open arrow head]. Moreover, there was no presence of dense glycogen accumulation at cell connections.


Glycogen and the propensity for atrial fibrillation: intrinsic anatomic differences in glycogen in the left and right atria in the goat heart.

Embi AA, Scherlag BJ, Ritchey JW - N Am J Med Sci (2014)

RAAs myocardium showing PAS staining (never as conspicuous as the LAA) Bar 1 mm. Please note that there is subepicardial glycogen concentration
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4215488&req=5

Figure 4: RAAs myocardium showing PAS staining (never as conspicuous as the LAA) Bar 1 mm. Please note that there is subepicardial glycogen concentration
Mentions: The present study demonstrates that in the normal caprine heart there are intrinsic quantitative differences in glycogen concentrations between the LAA and RAA. Both sides showed subepicardial presence of glycogen [Figures 4 and 5] that is notably displayed in a greater concentration in the LAA. The significantly greater glycogen in the LAA is heterogeneously found as high-density depositions against the intercalated discs and extending into the myocytes. Also condensed glycogen was observed at the sided to side junction of adjacent myocytes. In the RAA granules of glycogen were scattered throughout the cells. Although there were individual myocytes in which the glycogen granules outlined the intercalated disc and side to side myocyte junctions, many other cells did not show this pattern [Figure 1, open arrow head]. Moreover, there was no presence of dense glycogen accumulation at cell connections.

Bottom Line: Previous experimental studies have demonstrated electrophysiological and structural remodeling in pacing induced atrial fibrillation.We are reporting for the first time that the right atrial appendage showed scattered glycogen granules throughout the atrial myocytes which delineated the intercalated discs; whereas glycogen in the left atrial appendage was more dense within cells and coalesced against the intercalated discs and side to side junctions between myocytes.We show that glycogen is heterogeneously distributed in both atria in the normal goat heart; however, the density of glycogen deposits concentrating against the intercalated discs and side to side connections in the left atrial appendage is a critically distinct difference.

View Article: PubMed Central - PubMed

Affiliation: Independent, Miami, Florida, USA.

ABSTRACT

Background: Previous experimental studies have demonstrated electrophysiological and structural remodeling in pacing induced atrial fibrillation. The latter has been characterized by glycogen accumulation but no connection to atrial fibrillation induction and maintenance has as yet been proposed.

Aims: We determined the presence of glycogen in the right and left atrial appendages in the goat heart, in order to find any intrinsic disparity in distribution and concentration between these sites.

Materials and methods: Atrial appendages from 5 goats were stained by the Periodic acid Schiffmethod to determine the presence of glycogen and the concentration of glycogen by morphometric analysis.

Results: We are reporting for the first time that the right atrial appendage showed scattered glycogen granules throughout the atrial myocytes which delineated the intercalated discs; whereas glycogen in the left atrial appendage was more dense within cells and coalesced against the intercalated discs and side to side junctions between myocytes. Also, morphometric analysis determined that the stained regions of the right atrial appendages averaged, 0.8 ± 1.3 μm(2) compared to the left atrial appendage sections, 2.6 ± 3 μm(2), P = 0.02. We show that glycogen is heterogeneously distributed in both atria in the normal goat heart; however, the density of glycogen deposits concentrating against the intercalated discs and side to side connections in the left atrial appendage is a critically distinct difference. Impediment of cell to cell conduction could result in a non-uniform wavefront of activation, with areas of slowed conduction, predisposing the left atrium to reentrant based atrial fibrillation.

Conclusion: These findings provide a basis for the well-known greater propensity for atrial fibrillation in the left versus the right atrium.

No MeSH data available.


Related in: MedlinePlus