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Ion channels specificity

An exciting area in inclusion chemistry is the design and synthesis of molecules which could behave as ion channels. Future developments in this field offer the potential for developing new synthetic antibiotic molecules, model systems for investigating transport across membranes, and ion channels specific for particular ions. Such studies are so far only in their infancy. [Pg.188]

This model for the action potential postulated the existence of ion channels specific for Na and K. These channels must open in response to changes in membrane potential and then close after having remained open tor a brief period of time. This bold hypothesis predicted the existence of molecules with a well-defined set of properties long before tools existed for their direct detection and characterization. [Pg.362]

Receptor inactivation theory, initially proposed by Gosselin in 1977 has been widely disseminated by Kenakin (35)and to some degree is based on the two-state model originally proposed by Katz and Thesleff (41) for ion channels, specifically the Torpedo nicotinic receptor. where the multimeric receptor exists in active and inactive states, with ligand binding altering the equilibrium between these two states. Receptor inactivation theory reflects a synthesis of both occupancy and rate theories providing an alternative consideration for the study of the RL interaction. [Pg.326]

Currently, it is standard procedure to develop ion channel-specific antibodies for immunocytochemistry, to perform Western and Northern blot analyses, ion channel in situ hybridization, or reverse transcription polymerase chain reaction (RT-PCR). The introduction of the single-cell RT-PCR in combination with the patch-clamp method in the 1990s made it possible to identify gene transcripts and to correlate them with functional data for the same individual cell. Finally, one of the most powerful cell biological techniques in the study of ion channels is based on artificial expression systems such as microinjection of mRNA encoding channel subunits into Xenopus oocytes and selective expression of native ion channels or with different subunit composition (e.g., Ky channel subunits). Because the Xenopus oocytes are large, they are a perfect model to study artificially expressed channels. Another good model for artificial ion channel expression is the Chinese hamster ovary (CHO) cell line. [Pg.414]

We initially sought to explain the biochemical basis of venom-induced insect paralysis by spider venom components. Using an electrophysiological assay for synaptic transmission, we deflned three classes of ion channel specific toxins, the a-, p- and co-agatoxins from Agelenopsis aperta venom. Two different types of co-agatoxins (Types I and II) were found to block insect presynaptic calcium channels. [Pg.251]

However, the octanol/water partition coefficients do not completely reflect BBB permeability to solutes. Some solutes with low partition coefficients that easily enter into the CNS generally cross the BBB by active or facilitated transport mechanisms, which rely on ion channels, specific transporters,... [Pg.264]

Newel experimental approaches to anxiety therapy include ligands interacting with the ligand-gated ion channels that are selectively activated by nicotine, C qH 4N2 (87), the well-known active ingredient of cigarettes which has anxiolytic actions (42). Cholecystokinin B receptor ligands, specifically the dipeptoid, CI-988 [130404-91 -0] 02 1142 40 (88) have demonstrated anxiolytic activity ia preclinical models (43). [Pg.542]

Researchers at the MoneU Center (Philadelphia, Pennsylvania) are using a variety of electrophysical and biochemical techniques to characterize the ionic currents produced in taste and olfactory receptor cells by chemical stimuli. These studies are concerned with the identification and pharmacology of the active ion channels and mode of production. One of the techniques employed by the MoneU researchers is that of "patch clamp." This method aUows for the study of the electrical properties of smaU patches of the ceU membrane. The program at MoneU has determined that odors stimulate intraceUular enzymes to produce cycUc adenosine 3, 5 -monophosphate (cAMP). This production of cAMP promotes opening of the ion channel, aUowing cations to enter and excite the ceU. MoneU s future studies wiU focus on the connection of cAMP, and the production of the electrical response to the brain. The patch clamp technique also may be a method to study the specificity of receptor ceUs to different odors, as weU as the adaptation to prolonged stimulation (3). [Pg.292]

With few exceptions, information on the anticonvulsant pharmacology of specific ion channel subunits analyzed in expression systems is scarce. Hitherto, a first understanding of the mechanism of action of most antiepileptic dtugs has evolved from analyses of somatic ion channel pharmacology either in isolated neurons from human or rodent neurons, or cell culture models. [Pg.127]

Gating, a property of many ion channels, is the active transition between open and closed states in response to specific signals, such as membrane voltage or the presence of neurotransmitters. [Pg.525]

At a cellular level, the activation of mAChRs leads to a wide spectrum of biochemical and electrophysiological responses [1, 5]. The precise pattern of responses that can be observed does not only depend on the nature of the activated G proteins (receptor subtypes) but also on which specific components of different signaling cascades (e.g. effector enzymes or ion channels) are actually expressed in the studied cell type or tissue. The observed effects can be caused by direct interactions of the activated G protein(s) with effector enzymes or ion channels or may be mediated by second messengers (Ca2+, DP3, etc.) generated upon mAChR stimulation. [Pg.797]

Enterochromaffin cells are interspersed with mucosal cells mainly in the stomach and small intestine. In the blood, serotonin is present at high concentrations in platelets, which take up serotonin from the plasma by an active transport process. Serotonin is released on platelet activation. In the central nervous system, serotonin serves as a transmitter. The main serotonin-containing neurons are those clustered in form of the Raphe nuclei. Serotonin exerts its biological effects through the activation of specific receptors. Most of them are G-protein coupled receptors (GPCRs) and belong to the 5-HTr, 5-HT2-, 5-HT4-, 5-HTs-, 5-HT6-, 5-HT7-receptor subfamilies. The 5-HT3-receptor is a ligand-operated ion channel. [Pg.1120]


See other pages where Ion channels specificity is mentioned: [Pg.403]    [Pg.243]    [Pg.88]    [Pg.235]    [Pg.377]    [Pg.1091]    [Pg.13]    [Pg.403]    [Pg.393]    [Pg.418]    [Pg.418]    [Pg.13]    [Pg.532]    [Pg.250]    [Pg.255]    [Pg.403]    [Pg.243]    [Pg.88]    [Pg.235]    [Pg.377]    [Pg.1091]    [Pg.13]    [Pg.403]    [Pg.393]    [Pg.418]    [Pg.418]    [Pg.13]    [Pg.532]    [Pg.250]    [Pg.255]    [Pg.516]    [Pg.271]    [Pg.271]    [Pg.277]    [Pg.284]    [Pg.232]    [Pg.251]    [Pg.279]    [Pg.282]    [Pg.275]    [Pg.181]    [Pg.42]    [Pg.1]    [Pg.197]    [Pg.414]    [Pg.464]    [Pg.534]    [Pg.534]    [Pg.813]    [Pg.826]    [Pg.868]    [Pg.914]    [Pg.953]   
See also in sourсe #XX -- [ Pg.365 , Pg.367 ]




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Ion specifications

Specific ion

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