3.3 Presence of NO-synthases and antioxidant enzymes
Endothelial NO-synthase (eNOS or NOS3) was detected with
immunohistochemistry in most arteries investigated (Figure 3A). The
staining was faint, unevenly distributed over the arterial wall, not
restricted to the luminal endothelial layer but present in the tunica
media as well. Largely similar staining for eNOS was observed in small
arteries in the atrial appendage fixed immediately after isolation
during surgery (Figure 3B). This control was performed to exclude that
expression of eNOS had been modified during several hours of in vitro
investigation of the isolated resistance arteries investigated.
The other isozymes of NO-synthase were expressed as well in the
resistance arteries of the CVD patients. As was the case for eNOS,
staining of inducible NO-synthase (iNOS or NOS2) was faint, unevenly
distributed over the microvascular wall and detected in both endothelial
and smooth muscle cells (Figure 3C). Even though not directly comparable
due to the nature of the IHC, expression of neuronal NO-synthase (nNOS
or NOS1) was easily detectable, and thus seemed more abundant in the
resistance artery endothelium and smooth muscle compared to the other
NO-synthases and was often detectable in the tunica adventitia as well
(Figure 3D).
Endogenous catalase and Cu-Zn superoxide dismutase (SOD1) were detected
in far less patients compared to the NO-synthases and both were observed
primarily in the arterial smooth muscle cells (Figure 3E and 3F).