Mechanically gated ion channels

Mechanical transduction depends on activation of ion channels linked to extracellular and intracellular structures. A comprehensive model for hair-cell transduction has emerged, derived primarily from biophysical and morphological investigations. Residing in the mechanore-ceptive organelle of a hair cell, the hair bundle, the transduction apparatus consists of at least three components the transduction channel, a mechanically gated ion channel the tip link, an extracellular filament that transmits force to the channel s gate and the adaptation motor,... 

Eukaryotic cells have six general types of signaling mechanisms gated ion channels receptor enzymes membrane proteins that act through G proteins nuclear proteins that bind steroids and act as transcription factors membrane proteins that attract and activate soluble protein kinases and adhesion receptors that carry information between the extracellular matrix and the cytoslceleton. 

The del Castillo-Katz Mechanism 2. Interpretation of Efficacy for Ligand-Gated Ion Channels... 

The simplest agonist mechanism that can be used to describe activation of the ligand-gated ion-channel receptors is that first suggested by del Castillo and Katz (1957) for activation of nAChRs at the neuromuscular junction ... 

A simple mechanism for competitive antagonism of a ligand-gated ion-channel receptor would be as follows ... 

Three families of serotonin receptor, the 5-HT family, the 5-HT2 family and the family that includes the 5-HT4, 5-ht6 and 5-HT7 receptors represent the three major classes of 5-HT receptor that are G-protein-coupled receptors (Ch. 19). The 5-HT3 receptor is a ligand-gated ion channel and is a separate family. Although each serotonin receptor can be potently activated by 5-HT, differences insignal transduction mechanisms,neuroanatomical distribution and affinities for synthetic chemicals create opportunities for drug discovery and make each 5-HT receptor subtype a potential therapeutic target. 

However, it was not until over a century later that the underlying mechanism was explained in terms of the properties of the specific membrane proteins forming the voltage-gated ion channels of sodium and potassium ions. 

Amantadine. Early or mild parkinsonian manifestations may be temporarily reUeved by amantadine. The underlying mechanism of action may involve, inter alia, blockade of Ugand-gated ion channels of the glutamate/ NMDA subtype, ultimately leading to a diminished release of acetylcholine. 

Ion channels (center). These receptors contain ligand-gated ion channels. Binding of the signaling substance opens the channels for ions such as Na, Ca, and Cl . This mechanism is mainly used by neurotransmitters such as acetylcholine (nicotinic receptor see p.224) and GABA (A receptor see p.354). 

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