Fig 2: Representative histotopograms of TRPM6 images in the four chamber walls of the human heart. (a) Control subject after traffic accident. (b) IHD patient. The intensity of the brownish pigments shows areas with expression of TRPM6 in the heart (× 40 magnification). (c) Negative control (left) in the LV, and positive control (right) of TRPM6 in tumour of the colon (× 40 magnification). Scale bars indicate 100 µm. Other notations are the same as in Fig. 7.

Fig 3: TRPM7 and TRPM6 protein levels and RT-qPCR mRNA relative expression levels in human heart tissue homogenates. (a, b) TRPM7 and TRPM6 proteins are increased in the walls of all heart chambers with IHD (filled columns) vs. non-IHD (unfilled columns). A blinded study-design (with the diagnosis unknown to the investigator) was used for the detection of protein concentration in the various samples. Values (mean ± SEM) are in pg/mL and from 3–33 heart tissue homogenates. *P < 0.05 IHD vs. non-IHD, #P < 0.05 right-sided vs. left-sided using ANOVA with LSD test (Least Significant Difference). (c) mRNA relative expression levels of human Trpm6 and Trpm7 genes detected in the four cardiac chambers from explanted human hearts (n = 3, for each). *P < 0.05 Trpm7 vs. Trpm6, #P < 0.05 right-sided vs. left-sided.

Fig 4: Immunofluorescence images depicting co-expression of TRPM6 and TRPM7 proteins in human cardiomyocytes. (a) The immunofluorescence of TRPM7 (green) and TRPM6 (red) in the same LA, RA, LV, and RV cardiomyocyte when using conjugated antibodies (the arrowheads indicate the localization of TRPM6 protein in perinuclear area). (b) Quantification of the staining intensity of the immunodetected conjugated antibodies (spotty) and non-conjugated antibodies (smooth) for both proteins in cardiomyocytes from the four chambers of the heart as indicated. *P < 0.001 2 h vs. 12 h, #P < 0.001 right-sided vs. left-sided heart chambers. Other notations are the same as in Fig. 1.

Fig 5: Comparison of the levels of TRPM6 and TRPM7 in IHD vs. non-IHD. (a–d, e–h) Quantification of the intensity of fluorescence in cardiomyocytes obtained from patients with IHD (filled symbols) and without such diagnosis (unfilled symbols) expressed in arbitrary units (a.u.) in presence/absence of divalent cations, 2 h and 12 h, respectively. In all cells used P < 0.001 IHD vs. non-IHD. Other notations are the same as in Fig. 1. IHD increases the fluorescence level of the immunodetected TRPM7 (green) and TRPM6 (red) proteins expression.