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Purves D, Augustine GJ, Fitzpatrick D, et al., editors. Neuroscience. 2nd edition. Sunderland (MA): Sinauer Associates; 2001.

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Neuroscience. 2nd edition.

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Purinergic Receptors

Receptors for both ATP and adenosine are widely distributed in the nervous system, as well as many other tissues. Three classes of these purinergic receptors are now known. One of these classes is a ligand-gated ion channels (see Figure 7.11C); the other two are G-protein-coupled metabotropic receptors (see Figure 7.13B).

Like nicotinic receptors and ionotropic glutamate receptors, the ligand-gated channels are nonselective cation channels that mediate excitatory postsynaptic responses. The genes encoding these channels, however, indicate a subunit arrangement quite different from other ligand-gated ion channels in that there appear to be only two transmembrane domains. Ionotropic purinergic receptors are widely distributed in central and peripheral neurons. In sensory nerves they evidently play a role in mechanosensation and pain; their function in most other cells is unknown.

The two types of metabotropic receptors activated by purines differ in their sensitivity to agonists: One type is preferentially stimulated by adenosine, whereas the other is preferentially activated by ATP. Both receptor types are widely distributed in the brain, as well as in peripheral tissues such as the heart, adipose tissue, and the kidney. Xanthines such as caffeine and theophylline block adenosine receptors, and this ability is thought to account for their effects as behavioral stimulants.

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By agreement with the publisher, this book is accessible by the search feature, but cannot be browsed.

Copyright © 2001, Sinauer Associates, Inc.
Bookshelf ID: NBK10846


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