Cardiomyocytes preferentially expresses TrkA and cardiac fibroblasts TrkC.

<p><b>A</b>) TrkA levels are significantly higher in cardiomyocytes than in cardiac fibroblasts in tissue sections of the heart. <b>Left panel</b> shows the quantification of TrkA, vimentin (cardiac fibroblast marker), and myosin heavy chain (MHC, cardiomyocyte marker) identified by immunofluorescence on sections of C57BL/6 mouse hearts. Vimentin and MHC staining is plotted as function of TrkA fluorescence showing that TrkA is expressed by both cardiac fibroblasts and myocytes and that expression is higher in the myocytes. <b>Right panel</b> is a plot of vimentin and MHC mean fluorescence on pixels where TrkA is >200 (n = 3); ****, p<0.0001. <b>B</b>) TrkC levels are significantly higher in cardiac fibroblasts than on cardiomyocytes in tissue sections of the heart. <b>Left panel</b> shows the quantification of TrkC, vimentin, and MHC identified by immunofluorescence on sections of C57BL/6 mouse hearts, showing a preferential association of TrkC with cardiac fibroblasts. <b>Right panel</b> is a plot of vimentin and MHC mean fluorescence on pixels where TrkC is >200 (n = 3);****, p<0.0001.<b>C</b>) Visualization of the preferential expression of TrkA on cardiomyocytes in the heart. Representative images from the results presented in (<b>A</b>) above. Note preferential merge of TrkA and cardiomyocyte staining, scale bar = 100 µm. <b>D</b>) Visualization of the preferential expression of TrkC in cardiac fibroblasts in the heart. Representative images from the results presented in (<b>B</b>) above. Of note, TrkC staining merges preferentially in vimentin-stained cardiac fibroblasts, typically surrounding cardiomyocyte bundles, scale bar = 100 µm.