Endothelial Mediators and Renal Disease
Patrick J Vallance, David J. Webb in Vascular Endothelium in Human Physiology and Pathophysiology, 2000
As in other vascular beds, the endothelium of the renal vasculature synthesises mediators such as NO, prostaglandins and endothelin with potential to modulate blood vessel function. However, the endothelium is not the only cell type that synthesises these autacoids, and many renal parenchymal cells synthesise and respond to these mediators. This makes it difficult to be certain of the precise contribution of the endothelium to effects mediated by these agents. Moreover, the kidney is also responsible for the excretion of substances that might alter endothelial function, and as a result renal dysfunction could contribute to widespread endothelial abnormalities. In this chapter, we will review the role of endothelial mediators in the regulation of renal function with emphasis on human physiology and pathophysiology.
Chloride Channels in Endothelium: The Role of Mechano-stimulation and Changes in Cell Volume
Michael A Gimbrone, Peter Lelkes in Mechanical Forces and the Endothelium, 1999
One of the most exciting features of vascular endothelial cells (EC) is their ability to respond to mechanical stimuli. ECs are constantly exposed to mechanical forces such as shear forces resulting from blood flow and mechanical strain (biaxial tensile stress) which also induce changes in cell shape and possible folding and unfolding of the plasma membrane (Davies, 1995; Malek and Izumo, 1994). These forces activate a variety of biological responses, such as gating of mechano-and volume sensitive ion channels, and help to adjust the vessel diameter to the hemodynamic needs (Davies, 1995; Davies and Barbee, 1994; Davies and Tripathi, 1993; Nilius, 1991; Resnick and Gimbrone, 1995). Our current knowledge of the mechanisms that regulate such ion channels in endothelium is very limited. This article focuses on mechano-and volume sensitive ion channels in endothelium and in particular on Cl-channels.
Endothelium
Lara Wijayasiri, Kate McCombe in The Primary FRCA Structured Oral Examination Study Guide 1, 2010
What is the basic structure of endothelium? Endothelium refers to the simple squamous epithelium that is found lining organs, blood vessels and body cavities. This single layer of cells lies on top of a basement membrane, and in small arteries, arterioles and glands it is also in close proximity to smooth muscle. Endothelial structure varies according to its site and function. The major types include: ➤ Continuous endothelium consists of a continuous basement membrane with endothelial cells anchored together via tight junctions. It has a low permeability and is found in the blood brain barrier and the lung.
Contractions to Endothelin in Normotensive and Spontaneously Hypertensive Rats: Role of Endothelium and Prostaglandins
Published in Blood Pressure, 1992
Wolfgang Auch-schwelk, Paul M. Vanhoutte
Contractions to endothelin-1 in aortas of the spontaneously hypertensive rats (SHR) were compared with those of normotensive controls (WKY); rings with and without endothelium were studied in organ chambers. Contractions to endothelin were smaller in aortas of SHR compared to WKY, whether the endothelium was present or not. The presence of a functional endothelium reduced contractions to the peptide in both strains. Endothelium-dependent relaxations to acetylcholine and endothelium-independent relaxations to nitric oxide were observed in rings from both strains during contraction with endothelin. Indomethacin reduced the contractions to endothelin in the aorta from SHR with endothelium, but not in those without endothelium; it did not significantly affect endothelin-induced contractions in rings of WKY with or without endothelium. These experiments demonstrate that contractions of the vascular smooth muscle to endothelin are reduced in the aorta of the SHR. The basal and stimulated release of endothelium-derived relaxing factor inhibits contractions to endothelin in the aorta from both strains. The inhibitor of cyclooxygenase indomethacin does not prevent the response of the vascular smooth muscle to endothelin; however, endothelin may stimulate the release of an indomethacin-sensitive endothelium-derived contracting factor in the SHR aorta.
Hypoxia-Induced Contractions of Porcine Pulmonary Artery Strips Depend on Intact Endothelium
Published in Experimental Lung Research, 1984
Experiments were carried out to test the hypothesis that intact endothelium is required for hypoxia-induced contractions of pulmonary vascular muscle in vitro. To study this possibility, we cut pairs of transverse strips from main pulmonary arteries of pigs, removed the endothelium from one strip, and mounted the strips on force transducers in separate tissue baths. After an adaptation period of 4-6 h at an oxygen tension of 40 torr, strips with intact endothelium contracted spontaneously when the oxygen tension was decreased from 140 torr to near zero torr (6.5 ± 1.1 gm-wt/cm2, mean ± SEM) whereas strips without endothelium contracted significantly less (1.0 ± 0.3 gm-wt/cm2, p
The endocrine function of the vascular endothelium
Published in Journal of Biological Education, 1995
Jenny Henderson, Ian W. Henderson
The lining of the vasculature, a simple squamous epithelium — the endothelium — amounts in each human being to a total of I kg in weight and comprises several thousand million cells. The endothelium ts an interface between blood and extravascular spaces governing the passages of key products, among them nutrients, key immunological cells and waste products. Recent findings have shown that the endothelium is a major endocrine regulator of cardiovascular homeostasis by virtue of secreting a number of vasorelaxant and vasoconstrictive substances. A vasorelaxant material, originally described as Endothelium-Derived Relaxing Factor [EDRF], is now known to be nitric oxide. A vasoconstrictor material produced by the endothelium is endothelin. This peptide hormone is a member of a phylogenetically ancient family of gene products, originally identified in the venom of the Burrowing Asp. These two potential paracrine regulators are thought to pass from the endothelium to the neighbouring vascular smooth muscle, but they may have systemic actions. The endothelium is also a source of many other vasoactive factors and interactions between these, and both nitric oxide and endothelin, are the subjects of intensive contemporary investigation. The endothelium is now a recognized member of the endocrine system.