Ion channels最新文献_第3页

The inactivation of sodium channels in the node of Ranvier and its chemical modification. 朗维耶结钠离子通道失活及其化学修饰。

Ion channels Pub Date : 1990-01-01 DOI: 10.1007/978-1-4615-7305-0_4

W Ulbricht

{"title":"The inactivation of sodium channels in the node of Ranvier and its chemical modification.","authors":"W Ulbricht","doi":"10.1007/978-1-4615-7305-0_4","DOIUrl":"https://doi.org/10.1007/978-1-4615-7305-0_4","url":null,"abstract":"The many experimental studies reported demonstrate the complexity of what is termed inactivation, the decrease of current flow through sodium channels at maintained depolarization. Even at the normal resting potential of, say, -70 mV for a frog node of Ranvier, ca. 20% of the channels are closed and inactivated, i.e., incapable of passing current on a sudden depolarization, in contrast to the remaining 80% of closed but resting channels. The term inactivation has thus evolved from bulk current (\"macroscopic\") phenomena and is applied to channels although its single-channel (\"microscopic\") basis is not entirely clear and may even vary among preparations. It is conceivable that the macroscopic phenomenon may have more than a single microscopic cause; this point will probably not be settled until a physical description of the conformational states of the channel macromolecule becomes available. At any rate, channel transition into an inactivated closed state can be easily affected by numerous reagents of highly diverse chemical nature and, most likely, different primary sites of action as already suggested by the sidedness of effective application, e.g., iodate and endopeptidases to the inside, polypeptide toxins to the outside. But also the search for a common denominator, a secondary target of all these treatments, has not been very successful as demonstrated by the experiments with group-specific reagents. Since modification of inactivation is often accompanied by shifts in the voltage dependence of gating parameters, a target could be the \"voltage sensor\" of the channel, charged and/or dipolar components of the channel macromolecule that, by being moved in the electric field, somehow induce gating and whose movement is measured as gating current (e.g, Hille, 1984). The fraction of open channels as a function of membrane potential, F(E), may serve as an indicator. It may be simply shifted (to more negative potentials) as by veratridine (Leibowitz et al., 1987) or flattened (reduction of gating charge?) and shifted (in the positive direction) as by Anemonia sulcata toxin II (Ulbricht and Schmidtmayer, 1981) or chloramine-T (Drews, 1987). On the other hand, the steady-state inactivation curve is shifted to more negative potentials by the toxin (Ulbricht and Schmidtmayer, 1981), but to more positive potentials by chloramine-T (Wang, 1984a; Schmidtmayer, 1985). Obviously, modifiers may affect activation and inactivation quite differently, a result that touches on the question as to what extent inactivation derives its potential dependence from activation.(ABSTRACT TRUNCATED AT 400 WORDS)","PeriodicalId":77183,"journal":{"name":"Ion channels","volume":"2 ","pages":"123-68"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13139920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 13

Regulation of the ATP-sensitive potassium channel. atp敏感钾通道的调控。

Ion channels Pub Date : 1990-01-01 DOI: 10.1007/978-1-4615-7305-0_6

J R de Weille, M Lazdunski

引用次数: 37

The gating current of the node of Ranvier. 朗维耶节点的门控电流。

Ion channels Pub Date : 1990-01-01 DOI: 10.1007/978-1-4615-7305-0_3

H Meves

引用次数: 6

The role of nonprotein domains in the function and synthesis of voltage-gated sodium channels. 非蛋白结构域在电压门控钠通道的功能和合成中的作用。

Ion channels Pub Date : 1990-01-01 DOI: 10.1007/978-1-4615-7305-0_2

S R Levinson, W B Thornhill, D S Duch, E Recio-Pinto, B W Urban

引用次数: 20

ATP-activated channels in excitable cells. 可兴奋细胞中的atp激活通道。

Ion channels Pub Date : 1990-01-01 DOI: 10.1007/978-1-4615-7305-0_5

B P Bean, D D Friel

{"title":"ATP-activated channels in excitable cells.","authors":"B P Bean, D D Friel","doi":"10.1007/978-1-4615-7305-0_5","DOIUrl":"https://doi.org/10.1007/978-1-4615-7305-0_5","url":null,"abstract":"Extracellular ATP is an activator or modulator of ionic channels in a wide variety of excitable cells. There appears to be a class of related cation-permeable ATP-activated channels in skeletal muscle, cardiac muscle, smooth muscle, and neurons; the channels in the different cell types appear to be similar, but not identical, in their ionic selectivity, receptor selectivity, and pharmacology. In all cases, these channels reverse near 0 mV and activation by ATP produces an excitatory effect. Much remains to be learned about these channels, their possible existence and roles in other cell types, and their relation to other types of ligand-gated channels. It will be especially important to develop more specific pharmacological blockers (and activators) in order to distinguish subtypes and to assess their physiological role. Another type of channel, so far described only in cardiac atrial cells, is identical to the channels in cardiac atrial cells activated by ACh receptors; it will be interesting to see if this type of receptor-channel complex is also found in neurons or other cells. In a variety of cells, ATP also acts as a modulator of voltage-dependent channels and of channels activated by other transmitters. It seems very likely that more instances of such modulation will be described in years to come. Possible second-messenger pathways mediating such modulation remain to be elucidated.","PeriodicalId":77183,"journal":{"name":"Ion channels","volume":"2 ","pages":"169-203"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/978-1-4615-7305-0_5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12879615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 106

Analytical diffusion models for membrane channels. 膜通道的解析扩散模型。

Ion channels Pub Date : 1990-01-01 DOI: 10.1007/978-1-4615-7305-0_7

P Y Gates, K E Cooper, R S Eisenberg

引用次数: 13

Channel protein engineering. An approach to the identification of molecular determinants of function in voltage-gated and ligand-regulated channel proteins. 通道蛋白工程。鉴定电压门控和配体调节通道蛋白功能的分子决定因素的方法。

Ion channels Pub Date : 1990-01-01

M Montal

引用次数: 0

Ionic channels in ocular epithelia. 眼上皮中的离子通道。

Ion channels Pub Date : 1988-01-01 DOI: 10.1007/978-1-4615-7302-9_8

J L Rae, R A Levis, R S Eisenberg