Heterogeneity of T-Tubules in Pig Hearts.
<h4>Background</h4>T-tubules are invaginations of the sarcolemma that play a key role in excitation-contraction coupling in mammalian cardiac myocytes. Although t-tubules were generally considered to be effectively absent in atrial myocytes, recent studies on atrial cells from larger mam...
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2016-01-01
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| author | Hanne C Gadeberg Richard C Bond Cherrie H T Kong Guillaume P Chanoit Raimondo Ascione Mark B Cannell Andrew F James |
| author_facet | Hanne C Gadeberg Richard C Bond Cherrie H T Kong Guillaume P Chanoit Raimondo Ascione Mark B Cannell Andrew F James |
| author_sort | Hanne C Gadeberg |
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| description | <h4>Background</h4>T-tubules are invaginations of the sarcolemma that play a key role in excitation-contraction coupling in mammalian cardiac myocytes. Although t-tubules were generally considered to be effectively absent in atrial myocytes, recent studies on atrial cells from larger mammals suggest that t-tubules may be more numerous than previously supposed. However, the degree of heterogeneity between cardiomyocytes in the extent of the t-tubule network remains unclear. The aim of the present study was to investigate the t-tubule network of pig atrial myocytes in comparison with ventricular tissue.<h4>Methods</h4>Cardiac tissue was obtained from young female Landrace White pigs (45-75 kg, 5-6 months old). Cardiomyocytes were isolated by arterial perfusion with a collagenase-containing solution. Ca2+ transients were examined in field-stimulated isolated cells loaded with fluo-4-AM. Membranes of isolated cells were visualized using di-8-ANEPPS. T-tubules were visualized in fixed-frozen tissue sections stained with Alexa-Fluor 488-conjugated WGA. Binary images were obtained by application of a threshold and t-tubule density (TTD) calculated. A distance mapping approach was used to calculate half-distance to nearest t-tubule (HDTT).<h4>Results & conclusion</h4>The spatio-temporal properties of the Ca2+ transient appeared to be consistent with the absence of functional t-tubules in isolated atrial myocytes. However, t-tubules could be identified in a sub-population of atrial cells in frozen sections. While all ventricular myocytes had TTD >3% (mean TTD = 6.94±0.395%, n = 24), this was true of just 5/22 atrial cells. Mean atrial TTD (2.35±0.457%, n = 22) was lower than ventricular TTD (P<0.0001). TTD correlated with cell-width (r = 0.7756, n = 46, P<0.0001). HDTT was significantly greater in the atrial cells with TTD ≤3% (2.29±0.16 μm, n = 17) than in either ventricular cells (1.33±0.05 μm, n = 24, P<0.0001) or in atrial cells with TTD >3% (1.65±0.06 μm, n = 5, P<0.05). These data demonstrate considerable heterogeneity between pig cardiomyocytes in the extent of t-tubule network, which correlated with cell size. |
| format | Article |
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| institution | Kabale University |
| issn | 1932-6203 |
| language | English |
| publishDate | 2016-01-01 |
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| spelling | doaj-art-05e15242b8ac42268cd5f465f4792dbd2025-08-20T03:24:28ZengPublic Library of Science (PLoS)PLoS ONE1932-62032016-01-01116e015686210.1371/journal.pone.0156862Heterogeneity of T-Tubules in Pig Hearts.Hanne C GadebergRichard C BondCherrie H T KongGuillaume P ChanoitRaimondo AscioneMark B CannellAndrew F James<h4>Background</h4>T-tubules are invaginations of the sarcolemma that play a key role in excitation-contraction coupling in mammalian cardiac myocytes. Although t-tubules were generally considered to be effectively absent in atrial myocytes, recent studies on atrial cells from larger mammals suggest that t-tubules may be more numerous than previously supposed. However, the degree of heterogeneity between cardiomyocytes in the extent of the t-tubule network remains unclear. The aim of the present study was to investigate the t-tubule network of pig atrial myocytes in comparison with ventricular tissue.<h4>Methods</h4>Cardiac tissue was obtained from young female Landrace White pigs (45-75 kg, 5-6 months old). Cardiomyocytes were isolated by arterial perfusion with a collagenase-containing solution. Ca2+ transients were examined in field-stimulated isolated cells loaded with fluo-4-AM. Membranes of isolated cells were visualized using di-8-ANEPPS. T-tubules were visualized in fixed-frozen tissue sections stained with Alexa-Fluor 488-conjugated WGA. Binary images were obtained by application of a threshold and t-tubule density (TTD) calculated. A distance mapping approach was used to calculate half-distance to nearest t-tubule (HDTT).<h4>Results & conclusion</h4>The spatio-temporal properties of the Ca2+ transient appeared to be consistent with the absence of functional t-tubules in isolated atrial myocytes. However, t-tubules could be identified in a sub-population of atrial cells in frozen sections. While all ventricular myocytes had TTD >3% (mean TTD = 6.94±0.395%, n = 24), this was true of just 5/22 atrial cells. Mean atrial TTD (2.35±0.457%, n = 22) was lower than ventricular TTD (P<0.0001). TTD correlated with cell-width (r = 0.7756, n = 46, P<0.0001). HDTT was significantly greater in the atrial cells with TTD ≤3% (2.29±0.16 μm, n = 17) than in either ventricular cells (1.33±0.05 μm, n = 24, P<0.0001) or in atrial cells with TTD >3% (1.65±0.06 μm, n = 5, P<0.05). These data demonstrate considerable heterogeneity between pig cardiomyocytes in the extent of t-tubule network, which correlated with cell size.https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0156862&type=printable |
| spellingShingle | Hanne C Gadeberg Richard C Bond Cherrie H T Kong Guillaume P Chanoit Raimondo Ascione Mark B Cannell Andrew F James Heterogeneity of T-Tubules in Pig Hearts. PLoS ONE |
| title | Heterogeneity of T-Tubules in Pig Hearts. |
| title_full | Heterogeneity of T-Tubules in Pig Hearts. |
| title_fullStr | Heterogeneity of T-Tubules in Pig Hearts. |
| title_full_unstemmed | Heterogeneity of T-Tubules in Pig Hearts. |
| title_short | Heterogeneity of T-Tubules in Pig Hearts. |
| title_sort | heterogeneity of t tubules in pig hearts |
| url | https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0156862&type=printable |
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