Ventricular conduction system defects, fibrosis and cardiac hypertrophy associated with <i>Nkx2-5</i>-induced hypertrabeculation.

<p>(A) Whole-mount immunofluorescence with Contactin-2 on opened LV from control (Ctrl), <i>Nkx2-5</i>^{<i>ΔTrbE10</i>} (∆TrbE10) and <i>Nkx2-5</i>^{<i>ΔTrbE14</i>} (∆TrbE14) adult hearts. High magnifications of peripheral PFs are shown below beside the corresponding images treated with angiotool. Red lines indicate the PF, and blue dots the branch points. LBB: Left bundle branch; LFP: Left PFs. Scale bar = 1mm. (B-C) Quantification of PF (B) and branching density (C). (N = 3 hearts per group) Mean ± SD; **p<0.01 <i>Nkx2-5</i>^{<i>ΔTrbE10</i>} <i>vs</i> control, **p<0.01 <i>Nkx2-5</i>^{<i>ΔTrbE14</i>} <i>vs</i> control. (D) Immunofluorescence with Contactin-2 and WGA-cy3 antibodies on transversal sections at the mid-ventricular level from control (Ctrl), <i>Nkx2-5</i>^{<i>ΔTrbE10</i>} (∆TrbE10) and <i>Nkx2-5</i>^{<i>ΔTrbE14</i>} (∆TrbE14) adult hearts. Asterisks indicate papillary muscles. Scale bar = 1mm. (a-a’) High magnifications at the level of the interventricular septum (a) and a serial section stained with WGA-cy3 and Nkx2-5 (a’). Dotted lines indicate the size of cardiomyocytes and arrowheads Nkx2-5^- nuclei present only in <i>Nkx2-5</i>^{<i>ΔTrbE10</i>} and <i>Nkx2-5</i>^{<i>ΔTrbE14</i>} mutants hearts. Scale bar = 50μm. (E) Quantification of cardiomyocytes hypertrophy by counting the number of cardiomyocytes per frame on high magnification images of transversal sections. (n = 20–30 frames per heart; N = 3 mice per group). **p<0.002 <i>Nkx2-5</i>^{<i>ΔTrbE10</i>} and <i>Nkx2-5</i>^{<i>ΔTrbE14</i>} <i>vs</i> control. (F) Fibrosis was quantified by measuring the percentage of WGA positive area in the LV. These measures were performed for 3 sections of adult hearts at the level of the apex and at mid-ventricle from control (N = 3), <i>Nkx2-5</i>^{<i>ΔTrbE10</i>} (**p < 0,005 (apex) and **p< 0,002 (mid) <i>vs</i> control, N = 3) and <i>Nkx2-5</i>^{<i>ΔTrbE14</i>} ($ p < 0,02 (apex) and ^$$ p < 0,01 (mid) <i>vs Nkx2-5</i>^{<i>ΔTrbE10</i>}, N = 3).