Blood Vascular factors

In any blood vessel, the final integrated response to either neuronally released norepinephrine or to circulating epinephrine probably depends on the relative participation of at least four populations of a-adreno-ceptors postjunctional i- and az-adrenoceptors mediate constriction of vascular smooth muscle, while prejunctional and endothelial az-adrenoceptors mediate vasodilation. An understanding of the vessel vascular response to adrenomimetic drugs also must include the effects of drugs on adventitial innervation, smooth muscle, and other vascular factors that may be present. 

By means of the complex process of haemostasis, the organism seeks to protect itself spontaneously against bleeding and the corresponding loss of blood. Three components are available to this end (J.) blood vessels themselves (= vascular haemostasis), (2.) platelets and endothelial cells (= cellular haemostasis), and (J.) blood-clotting factors (= plasmic blood coagulation). 

Vascular Factors in Blood Coagulation 413 Fibrinolysis 413 Thrombi and Emboli 415... 

Levy MN (1979) The cardiac and vascular factors that determine systemic blood flow. Circ Res 44 739-746... 

According to Blau et al. f88,89), the vascular factor is more important. In exercised animals, vessels inside the canal are dilated and if the canal is narrow increased blood supply is prevented, thus leading to ischemia of the cord and the nerve roots. However, this explanation is not shared by others (90). It does not explain why neurogenic claudication occurs in the lordotic position at rest. Pseudoclaudication can be caused by other orthopedic conditions of the hips, knees, and other joints. 

Factor VII. This is a vitamin K-dependent serine protease that functions in the extrinsic coagulation pathway and catalyzes the activation of Factors IX and X. Factor VII is present constitutively in the surface membrane of pericytes and fibroblasts in the adventitia of blood vessels, vascular endothehum, and monocytes. It is a single-chain glycoprotein of approximately 50,000 daltons. 

Yancopoulos GD, Davis S, Gale NWetal (2000) Vascular-specific growth factors and blood vessel formation. Nature 407 242-248... 

The human histamine Hi-receptor is a 487 amino acid protein that is widely distributed within the body. Histamine potently stimulates smooth muscle contraction via Hi-receptors in blood vessels, airways and in the gastrointestinal tract. In vascular endothelial cells, Hi-receptor activation increases vascular permeability and the synthesis and release of prostacyclin, plateletactivating factor, Von Willebrand factor and nitric oxide thus causing inflammation and the characteristic wheal response observed in the skin. Circulating histamine in the bloodstream (from, e.g. exposure to antigens or allergens) can, via the Hi-receptor, release sufficient nitric oxide from endothelial cells to cause a profound vasodilatation and drop in blood pressure (septic and anaphylactic shock). Activation of... 

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