Endothelial and vascular smooth muscle function in sepsis.

The vascular abnormalities that arise during sepsis imply disturbances in the delicately tuned homeostatic mechanisms of vascular endothelium and smooth muscle. In the microvasculature, smooth muscle tone represents a complex equilibrium among metabolic stimuli, hemodynamic forces, and neurohumoral influences. Local tissue perfusion also is modulated by vasoactive mediators that can be produced locally, through endothelium-dependent adhesion and activation of inflammatory cells, or at a distance. In sepsis, derangement of normal autoregulation of perfusion, together with toxic effects of mediators, may be severe enough to result in organ dysfunction. Recent advances in vascular biology have illuminated a variety of targets, such as adhesion molecules, platelet activating factor, and inducible nitric oxide synthase for potential therapeutic intervention in sepsis.