DOI: 10.5061/dryad.fb300
title: Data from: Heterogeneity of t-tubules in pig hearts

description: Background: 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. Methods: 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). Results & Conclusion: 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 &gt;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&lt;0.0001). TTD correlated with cell-width (r = 0.7756, n = 46,
 P&lt;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&lt;0.0001) or in atrial cells with TTD &gt;3%
 (1.65±0.06 μm, n = 5, P&lt;0.05). These data demonstrate considerable
 heterogeneity between pig cardiomyocytes in the extent of t-tubule
 network, which correlated with cell size.
description: Folder 1 -
 linescansFolder contains
 linescans in TIF format of the four atrial cells referred to in Figure 1
 of the manuscript.Folder 2 -
 di-8-ANEPPSA folder containing two
 further folders ('atrial' and 'ventricular'), which
 contain, respectively, TIF images of the 10 atrial and 4 ventricular
 di-8-ANEPPS-stained cells referred to in Figure 2.Folder 2 -
 di-8.7zSham v control
 TTDA
 spreadsheet containing t-tubule densities (TTD) of atrial and ventricular
 cells from Sham and Control animals to establish that there was no
 difference the t-tubule network in either atrial or ventricular cells
 between these two groups of animals.Pig TTD A V Sham vs
 control.xlsxControl atrial
 1Original images of
 sections from atrial tissue from control animals used for analysis
 presented in Figures 4 - 6. Folder 1 of 5.Control atrial
 2Original images of
 sections of atrial tissue from control animals used for analysis shown in
 Figures 4 - 6. Folder 2 of 5.Sham
 atrialOriginal images of
 atrial sections from Sham animals used for analysis presented in Figures 4
 - 6. Folder 3 of 5.Control
 ventricularOriginal images of
 ventricular sections from control animals used for analysis presented in
 Figures 4 - 6. Folder 4 of 5.Sham
 ventricularOriginal images of
 sections from ventricular cells from Sham animals used for analysis
 presented in Figures 4 - 6. Folder 5 of 5.