Vascular smooth muscle cells in various blood vessels express all three nitric oxide synthase isoforms, suggesting an endothelium-independent mechanism for modulating vascular functions.
This study provides the first evidence that vascular smooth muscle cells express all three NOS isoforms, suggesting an endothelium-independent mechanism for local NOS modulation of vascular functions.
The concept of endothelium-derived relaxing factor (EDRF) put forward in 1980 by Furchgott and Zawadzki implies that nitric oxide (NO) produced by NO synthase (NOS) in the endothelium diffuses to the underlying vascular smooth muscle, where it modulates vascular tone as well as vascular smooth muscle cell (VSMC) proliferation by increasing cGMP formation with subsequent activation of cGMP-dependent protein kinase. According to this concept, VSMC do not express NOS by themselves. This attractive, simple scheme is now under considerable debate. To address this issue, we designed this study with the use of a novel supersensitive immunocytochemical technique of signal amplification with tyramide and electron microscopic immunogold labeling complemented with Western blotting, as in our recent studies demonstrating NOS in the myocardial and skeletal muscles. We provide the first evidence that, in contrast to the currently accepted view, VSMC in various blood vessels express all three NOS isoforms depending on the blood vessel type. These findings suggest an alternative mechanism by which local NOS expression may modulate vascular functions in an endothelium-independent manner.
Buchwalow et al. (Mon,) reported a other. Nitric oxide synthase (NOS) expression was evaluated on Expression of NOS isoforms in vascular smooth muscle cells. Vascular smooth muscle cells in various blood vessels express all three nitric oxide synthase isoforms, suggesting an endothelium-independent mechanism for modulating vascular functions.