Immunohistologic localization of NTPDases in cardiac vasculature.

Serial sections of a mouse heart were stained by immunohistochemistry with various antibodies detecting (A) NTPDase1, (B) NTPDase2, (C) α-actin (a marker of smooth muscle), (D) CD31 (a marker of endothelium), (E) NG2 (a marker of pericytes and smooth muscle cells), and (F) laminin (a marker of basement membranes). Positive reactions were seen as rust color (A-F), and sections were counterstained with hematoxylin (blue). In panels G-I, immunofluorescence and confocal analysis were performed: (G) CD31 in blue and NTPDase1 in green (colocalization as aquamarine); (H) as for panel G with addition of NTPDase2 in red; (I) NTPDase1 in green, smooth muscle α-actin in blue, and NTPDase2 in red (no colocalization). In medium-sized vessels, CD31 and NTPDase1 were found to colocalize while NTPDase2 did not colocalize with these 2 markers or the smooth muscle α-actin–expressing cells. Original magnifications, ×200.