Acetylcholine tissue distribution

LaRochelle, W.J., and Froehner, S.C. (1986a) Determination of the tissue distributions and relative concentrations of the postsynaptic 43-kDa protein and the acetylcholine receptor in Torpedo. J. Biol. Chem. 261, 5270-5274. 

Not surprisingly, different ligands exhibit a characteristic individual affinity profile at the subtypes of the nicotinic acetylcholine receptors (Tab. 8.2). [131] These compounds served as suitable tools to investigate the tissue distribution of such receptors in the central and peripheral nervous systems. 

It is well established that acetylcholine can be catabolized by both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) these are also known as "true" and "pseudo" cholinesterase, respectively. Such enzymes may be differentiated by their specificity for different choline esters and by their susceptibility to different antagonists. They also differ in their anatomical distribution, with AChE being associated with nervous tissue while BChE is largely found in non-nervous tissue. In the brain there does not seem to be a good correlation between the distribution of cholinergic terminals and the presence of AChE, choline acetyltransferase having been found to be a better marker of such terminals. An assessment of cholinesterase activity can be made by examining red blood cells, which contain only AChE, and plasma. 

Many receptors have been identified in all cases they are proteins. Some of the proteins have enzymatic activity. Eor instance, dihydrofolate reductase is a receptor for antifolates and acetylcholine esterase is a receptor for organophosphates. Some receptors serve as transport vehicles across the cellular membranes, as is the case with the receptors for steroid hormones (Baxter and Eorsham, 1972). Specific receptors may be confined to certain tissues or may be distributed among all the cells of an organism. 

Nicotinic acetylcholine receptors (nAChRs) are a family of ligand-gated ion channels that are found in abundance at the neuromuscular junction, and are widely distributed throughout the central and peripheral nervous systems. They comprise five subunit proteins that combine to form a cation permeable pore at the cell surface. In neuronal tissues, multiple nAChR subtypes may be assembled from a diverse array of subunits (a2-a9 32-p4) and their... 

A) Nitric oxide is synthesized in vascular endothelium and the brain Nitric oxide is released from storage vesicles by acetylcholine Nitric oxide is released from exogenous molecules, eg, nitrates and nitroprusside Nitric oxide synthase is stimulated by histamine Nitric oxide synthase exists in both inducible and constitutive forms With regard to distribution of a drug from the blood into tissues (A) Blood flow to the tissue is an important determinant... 

OP and CM insecticides have a high affinity for binding to and inhibiting the enzyme AChE, an enzyme specifically responsible for the destruction of the neurotransmitter acetylcholine (ACh) within nerve tissue (Wilson, 2001 Ecobichon, 2001b). Since the cholinergic system is widely distributed within both the central and peripheral nervou.s systems, chemicals that inhibit AChE are known to produce... 

One of the pillars upon which rests the prevailing theory of the chemical mediation of nerve impulses is the uniqueness, in conducting tissue, of the enzyme that hydrolyzes acetylcholine. The characteristics of acetylcholinesterase that distinguish it from the other cholinesterases are as follows (1) A small Km when acetylcholine is the substrate. (2) Inhibition of the hydrolysis of acetylcholine by the substrate so that when the velocity is plotted against substrate concentration a bell-shaped curve results. (3) A rate of hydrolysis that is greatest with acetylcholine, less with propionylcholine, and the least with butyrylcholine. None of these properties is shared by the other cholinesterases. Acetylcholinesterase occurs, however, not only in conducting tissue but also in erythrocytes and cobra venom. The distribution of cholinesterases has been reviewed by Augustinsson. ... 

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