Figure 1. Distribution of α2 Na⁺ pumps and NCX1 in embryonic mouse (A and B) and human (C and D) artery smooth muscle determined by immunocytochemistry .

A, α2 Na⁺ pumps (green) and the plasma membrane Ca²⁺ pump (PMCA, red) are not co‐localized (negligible white areas) in this pseudocolour overlay image of a mouse aorta myocyte. B, α2 Na⁺ pumps (green) and NCX1 (red) exhibit substantial co‐localization (white areas) in a mouse aorta myocyte. C, primary cultured human mesenteric artery smooth muscle cells (hASMCs) were labelled with anti‐α2 polyclonal antibodies (pAb) and anti‐NCX1 monoclonal antibodies (mAb); the SR was then stained with ER‐Tracker, as indicated by the labels. Insets are enlargements of the boxed areas. Pseudocolour images of the enlarged α2 (red) and NCX1 (green) regions, and the overlay, are shown on the right. D, hASMCs were cross‐reacted with anti‐NCX1 mAb and anti‐TRPC6 pAb; the SR was then stained with ER‐Tracker, as indicated. Insets are enlargements of the boxed areas. Pseudocolour images of the enlarged NCX1 (green) and TRPC6 (red) regions, and the overlay, are shown on the right. In C and D, the patterns of staining by both antibodies were very similar to the pattern of ER Tracker (i.e. SR) distribution. Scale bars in C and D = 30 μm. Note that the α2, NCX1 and TRPC6 staining patterns are all very similar to that of ER‐Tracker. This is reflected by the yellow‐orange staining in the C and D overlay panels, and indicates that hASMC α2 Na⁺ pumps and NCX1 co‐localize (as in the mouse, B) and overlie elements of SR. A and B were kindly provided by Dr Ronald P. Lynch (B is from Lynch et al. 2008 with permission); C and D are from Linde et al. (2012) with permission.