Vascular endothelial cell preparation

Fig. 2. Intratumoral distribution of DilCIS-labeled liposomes in the orthotopic pancreatic tumors. Mice with orthotopic pancreatic tumor were injected with PEG-Lip or APRPG-PEG-Lip labeled with Dil Cl 8 via a tail vein at the day 3,9, and 18 after tumor implantation. At 2 h after injection of fluorescence-labeled liposomes, frozen-sections of each tumor were prepared. Green portions indicate CD31-positive regions, red portions liposomal distribution, and yellow portions show the localization of liposomes at the site of vascular endothelial cells. Scale bar represents lOOgm. Reproduced with permission from (7)...

Heparin has been used clinically for decades to prevent and treat thromboembolic disease and is isolated on an industrial scale from animal tissues, in particular pig intestinal mucosa. The conesponding physiological blood anticoagulant is presumably not heparin, but an HS species that is located on the surface of vascular endothelial cells. Both heparin and HS contain a specific pentasaccharide sequence that binds and activates the plasma proteinase inhibitor AT. This pentasaccharide sequence (4) is present only in a subfraction of heparin and HS preparations. It displays a characteristic structural feature, namely a 3-0-sulfated GlcN residue, that is only rarely seen in other portions of heparin/HS chains. 

Muscarinic agonists release endothelium-derived relaxing factor, identified as nitric oxide (NO), from the endothelial cells. The NO diffuses to adjacent vascular smooth muscle, where it activates guanylyl cyclase and increases cGMP, resulting in relaxation (see Figure 12-2). Isolated vessels prepared with the endothelium preserved consistently reproduce the... 

The second indication came from studies of vascular regulation. Several molecules, such as acetylcholine, were known to cause relaxation of blood vessels. This effect occurred only when the vessels were prepared so that the luminal endothelial cells covering the smooth muscle of the vessel wall were retained. Subsequent studies showed that endothelial cells respond to these vasorelaxants by releasing a soluble endothelial-derived relaxing factor (EDRF). EDRF acts on vascular muscle to elicit relaxation. These findings prompted an intense search for the identity of EDRF. 

UHT—ultrahigh temperature—food prepared during partial sterilization by heating it for a short time, around 1-2 s, at a temperature exceeding 135°C VC—Netherlands Nutrition Centre VCAM-1—vascular cell adhesion molecule-1 VEGF—vascular endothelial growth factor VIP—vasoactive intestinal peptide... 

Techniques have been developed for study of the renal microcirculation. These techniques have distinct advantages over in vitro endothelial and vascular smooth muscle cell preparations. They allow study of important anatomic and physiologic relationships that are lost in isolated cell systems. For example, the effects of both pressure and flow can be determined and the spatial relahonship between the endothelium and smooth muscle is maintained. These techniques permit functional assessment of the resistance micro-vasculature without destroying vessel integrity while eliminating the confounding influence of undetected circulating, neural and parenchymal factors. The techniques are demonstrated in Table 8. 

The hmitations of the preparation are ) autocoid production and vascular reactivity may be altered in vitro, 2) the absence of flow dynamics may alter endothelial cell function, 3) the small amount of tissue limits biochemical measurements, 4) isolated arterioles do not exhibit myogenic responses to changes in transmural pressure. 

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