ISSN:1062-4821    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

The natriuretic peptide system is a complicated system comprising at least three endogenous peptides (atrial natriuretic peptide, brain natriuretic peptide and C-type natriuretic peptide) and three receptors [the atrial natriuretic peptide-A receptor (guanylyl cyclase B), the atrial natriuretic peptide-B receptor (guanylyl cyclase B) and the clearance receptor]. The accumulated evidence indicates that this system is implicated in the control of blood pressure, body fluid homeostasis and vascular remodelling as cardiac hormone and local regulator.

ISSN:1062-4821    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Application of gene knockout techniques to endothelin research has led to the revelation of unexpected and interesting roles for endothelin isopeptides and their receptors. Homozygous mice with null endothelin-1 and ETAreceptors presented with craniofacial and cardiovascular malformations, indicating that these receptors are essential for the development of the first branchial arch derived from the neural crest. Homozygous mice with null endothelin-3 and ETBreceptors presented with megacolon (Hirschsprung's disease) associated with spotted colour coats, indicating that these latter receptors are essential for the development of neural crest-derived cell lineage, enteric neuron and epidermal melanocytes. Isolation and characterization of endothelin-converting enzyme which cleaves big endothelin-1, an intermediate form, into mature endothelin-1 has revealed a type II integral membrane-bound metalloprotease that is structurally homologous to neutral endopeptidase. Development of selective inhibitors for endothelin-converting enzyme isoenzymes will facilitate a greater understanding of the role of endogenous endothelin isopeptides.

ISSN:1062-4821    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Renin synthesisin vivois feedback regulated by the plasma angiotensin II concentration, the intrarenal pressure, the salt loading of the organism and the macula densa mechanism. At the level of renal juxtaglomerular cells renin synthesis is regulated by cyclic AMP, by nitric oxide and by the cytosolic calcium concentration. Cyclic AMP and nitric oxide are stimulators, whereas calcium is an inhibitor of renin synthesis.

ISSN:1062-4821    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Lipoxins are arachidonate-derived lipid mediators that are structurally and functionally distinct from other classes of eicosanoids. They are generated via transcellular pathways that initially involve the dual lipoxygenation of arachidonic acid either by 15− and 5-lipoxygenases or by 5− and 12− lipoxygenases (lipoxygenaseinteraction products). Platelet-neutrophil interactions are a particularly rich source of lipoxins within the vascular lumen. Cell-cell adhesion and cytokines are important amplifiers of these complex biosynthetic circuits. Leukocytes and endothelial cells express high affinity receptors for lipoxins, engagement of which evokes a unique profile of signal transduction events and bioactivities. In many assay systems, lipoxins prevent chemotaxis, adhesion, and transmigration of neutrophils induced by leukotrienes and other mediators, suggesting that lipoxins may act as endogenous braking signals in host defense, inflammation, and hypersensitivity reactions. Intriguingly, cyclo-oxygenase II, in the presence of aspirin, catalyses the formation of a novel series of 15-epi-lipoxins during neutrophil-endothelial cell interactions, suggesting a new mechanism of action for this commonly used therapeutic agent.

ISSN:1062-4821    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Oxygen-dependent changes of erythropoietin production in liver and kidneys provide the basis for a highly efficient feedback control of erythropoiesis. Peritubular fibroblasts in the renal cortex, hepatocytes and perisinusoidal Ito cells in the liver have recently been identified as the cellular sites of erythropoietin synthesis. The major control of erythropoietin production occurs at the level of its mRNA and involves changes in erythropoietin gene transcription rate. Modulation of renal erythropoietin mRNA levels is predominantly caused by changes in the number of fibroblasts in which the gene is active, but the cellular control of erythropoietin gene activity in these cells remains elusive. In hepatocytes, however, several characteristics and components of the control of erythropoietin production have been identified in recent years, including the binding of hypoxia-inducible proteins to specific regulatory elements of the erythropoietin gene.

ISSN:1062-4821    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:1062-4821    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Vascular endothelial growth factor is a diffusible endothelial cell-specific mitogen and angiogenic factor that can also increase vascular permeability. The vascular endothelial growth factor receptors are specifically expressed on the cell surface of vascular endothelial cells. Recent studies point to vascular endothelial growth factor as a major regulator of physiological angiogenesis, such as developmental and reproductive angiogenesis. In addition vascular endothelial growth factor appears to be a crucial mediator of blood vessel growth associated with tumors and proliferative retinopathies. Antivascular endothelial growth factor antibodies have the ability to suppress the growth of a variety of tumor cell lines in nude mice and can also inhibit angiogenesis in animal models of intra-ocular neovascularization. Furthermore vascular endothelial growth factor administration promotes collateral vessel growth and results in functional improvement in animal models of coronary or limb ischemia.

ISSN:1062-4821    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

The recent cloning of G protein-coupled extracellular Ca2+(Ca2+o)-sensing receptors from bovine (and human) parathyroid and rat kidney (and brain) has clearly shown that Ca2+ocan function as a ‘first messenger’. The physiological relevance of this receptor in Ca2+ohomeostasis in man has been demonstrated by the identification both of ‘inactivating’ and of ‘activating’ mutations in this Ca2+o-sensing receptor, which result in hypercalcemic and hypocalcemic phenotypes, respectively. The molecular mechanisms involved in extracellular calcium ‘sensing’ in the kidney are just beginning to emerge but are already suggesting new and novel mechanisms for linking Ca2+(and Mg2+) and water excretion. The latter interrelationship appears to be crucial because maximal water conservation during periods of increased urinary Ca2+or Mg2+loss (e.g. due to increased dietary intake of these solutes) would increase urinary divalent cation concentration and enhance the risk of crystal/stone formation. The interactions among Ca2+, NaCl and water handling in the distal nephron and collecting duct may provide mechanisms for integrating and balancing water and divalent mineral loss, minimizing the risk of stone formation (a ‘trade-off’ of water conservation for Ca2+or Mg2+loss). Research over the next few years should greatly expand our understanding of the roles played by this Ca2+o-sensor both in divalent mineral excretion and in water metabolism as well as in other tissues (e.g. in the central nervous system).

ISSN:1062-4821    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:1062-4821    

出版商:OVID    

年代:1996

数据来源: OVID