Nitric oxide functions

Soluble forms of guanylyl cyclase are activated by nitric oxide 370 Nitric oxide functions as an intracellular second messenger 370... 

De Graaf JC, Banga JD, Moncada S, Palmer RM, de Groot PG, Sixma JJ. Nitric oxide functions as an inhibitor of platelet adhesion under flow conditions. Circulation 85 2284-2290,199Z... 

The action of inhibitors is not so simply described, since they may act in a number of different ways. An inhibitor may slow a radical chain reaction by combining with the radicals nitric oxide functions in this way. In other cases, the inhibitor is consumed by combination with one of the reactants and only delays the reaction until it is used up. Some inhibitors may simply poison a trace of catalyst whose presence is unsuspected. 

It has been suggested that such a mechanism would be facilitated by a transition state in which the nitric oxide functions as the NO ligand, thus leaving a vacant, low-energy orbital on the metal. The influence of such other factors as 7r-bonding, ligand basicity, and solvent character have also been discussed (90), The exchange of with Co(NO)(CO)3 has also been studied. In toluene solutions it is slow and takes place by a first-order process, zero-order in (CO) (96). Preliminary data on the reaction of triphenylphosphine with Mn(NO)(CO)4 have been reported (17a). 

Biodegradable Biomaterials Having Nitric Oxide Function... 

Nitric Oxide. Nitric oxide [10102-43-9] NO, is a ubiquitous intracellular and intercellular messenger serving a variety of functions including vasodilation, cytotoxicity, neurotransmission, and neuromodulation (9). NO is a paramagnetic diatomic molecule that readily diffuses through aqueous and hpid compartments. Its locus of action is dictated by its chemical reactivity and the local environment. NO represents the first identified member of a series of gaseous second messengers that also includes CO. 

In addition to intracellular heme-containing proteins, big-conductance calcium-dependent K+ (BKCa) channels and calcium-spark activated transient Kca channels in plasma membrane are also tar geted by CO [3]. As well known, nitric oxide (NO) also activates BKca channels in vascular smooth muscle cells. While both NO and CO open BKCa channels, CO mainly acts on alpha subunit of BKCa channels and NO mainly acts on beta subunit of BKca channels in vascular smooth muscle cells. Rather than a redundant machinery, CO and NO provide a coordinated regulation of BKca channel function by acting on different subunits of the same protein complex. Furthermore, pretreatment of vascular smooth muscle... 

Toda N, Ayajiki T, Okamura T (2005) Nitric oxide and penile erectile function. Pharmacol Ther 106 233-266... 

The secretion of extracellular matrix proteins is also a function of smooth muscle cells but, since it occurs concurrently with other activities, it does not seem to constitute a physiological state. However, the fraction of the cellular resources which are devoted to it must be regulated these regulatory mechanisms are virtually unknown. In addition, it should be anticipated that autocrine activity occurs as well, involving peptides, prostaglandins, cytokines, and nitric oxide. 

While the fluid mosaic model of membrane stmcture has stood up well to detailed scrutiny, additional features of membrane structure and function are constantly emerging. Two structures of particular current interest, located in surface membranes, are tipid rafts and caveolae. The former are dynamic areas of the exo-plasmic leaflet of the lipid bilayer enriched in cholesterol and sphingolipids they are involved in signal transduction and possibly other processes. Caveolae may derive from lipid rafts. Many if not all of them contain the protein caveolin-1, which may be involved in their formation from rafts. Caveolae are observable by electron microscopy as flask-shaped indentations of the cell membrane. Proteins detected in caveolae include various components of the signal-transduction system (eg, the insutin receptor and some G proteins), the folate receptor, and endothetial nitric oxide synthase (eNOS). Caveolae and lipid rafts are active areas of research, and ideas concerning them and their possible roles in various diseases are rapidly evolving. 

Nitric Oxide Relaxes the Smooth Muscle of Blood Vessels Also Has Many Other Important Biologic Functions... 

Nitric oxide is a regulator of vascular smooth muscle blockage of its formation from arginine causes an acute elevation of blood pressure, indicating that regulation of blood pressure is one of its many functions. 

After an overview of neurotransmitter systems and function and a consideration of which substances can be classified as neurotransmitters, section A deals with their release, effects on neuronal excitability and receptor interaction. The synaptic physiology and pharmacology and possible brain function of each neurotransmitter is then covered in some detail (section B). Special attention is given to acetylcholine, glutamate, GABA, noradrenaline, dopamine, 5-hydroxytryptamine and the peptides but the purines, histamine, steroids and nitric oxide are not forgotten and there is a brief overview of appropriate basic pharmacology. 

In the preceding chapters, the synaptic pharmacology of those substances clearly established as NTs in the CNS, i.e. glutamate, GABA, ACh, NA, DA, 5-HT and certain peptides, has been discussed in some detail. There are other substances found in the CNS that could have a minor transmitter role, e.g. ATP, histamine and adrenaline, while still others that cannot claim such a property but clearly modify CNS function in some way, e.g. steroids, prostaglandins and nitric oxide. We will consider each of them in what we hope is appropriate detail. 

The results of a number of studies demonstrate that the gas nitric oxide (NO) plays a functional role in the central nervous system. This all originated with the discovery that the so-called endothelium-derived relaxing factor (EDRF), found in blood vessels, and thought to be a peptide, was in fact NO. The potential roles of this freely diffusible gas have subsequently been extended to many other tissues and organs but we will concentrate on the possible neuronal roles of what is obviously a novel mediator. There are also suggestions that the closely related carbon monoxide may also have a function in the central nervous system. 

Nonaqueous Systems In nonaqueous (nonpolar) solvent systems, nitrosatlon also proceeds. In these solvents, alpha-tocopherol acts as a lipid soluble blocking agent in much the same fashion as ascorbic acid functions in the aqueous phase. Alpha-tocopherol reacts with a nitrosating agent and reduces it to nitric oxide. At the same time, alpha-tocopherol is oxidized to tocoquinone, which is the first oxidation product of vitamin E and also a normal metabolite in vivo. 

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