ABSTRACT
The release and the effects of endothelium-derived relaxing factor (EDRF) and endothelium-derived contracting factor (EDCF) can be studied most easily in isolated blood vessels or with the use of cultured endothelial cells. To determine the endothelial origin of the factor(s) in isolated blood vessels, the vascular responsiveness of the preparations is compared in the presence and absence of the endothelium. In vitro, the endothelium can be removed either mechanically or chemically. For the mechanical removal, the blood vessels most commonly are placed on paper towels soaked with saline. Morphological studies using conventional histological or electron microscopic techniques demonstrate the effectiveness of these interventions to remove endothelial cells. In vivo, the endothelium of large conduit arteries can be removed by means of a balloon catheter without damaging the underlying vascular smooth muscle.
