Examples ion channels

Ca + is mobilized from two pools for elevating intracel-lulai levels the extracellular space and frem inti acellular endoplasmic reticulum (ER). Give examples ion channels on the plasma and the ER membranes that are used for mobilizing Ca +. 

An important characteristic of both classes of ion channel is that they possess multiple dmg binding sites (Table 2). Many of the channel-active dmgs have achieved particular therapeutic importance, including, for example, the Ca " antagonists, widely used for a number of cardiovascular disorders. 

Maintenance of electrical potential between the cell membrane exterior and interior is a necessity for the proper functioning of excitable neuronal and muscle cells. Chemical compounds can disturb ion fluxes that are essential for the maintenance of the membrane potentials. Fluxes of ions into the cells or out of the cells can be blocked by ion channel blockers (for example, some marine tox-... 

Whereas the main challenge for the first bilayer simulations has been to obtain stable bilayers with properties (e.g., densities) which compare well with experiments, more and more complex problems can be tackled nowadays. For example, lipid bilayers were set up and compared in different phases (the fluid, the gel, the ripple phase) [67,68,76,81]. The formation of large pores and the structure of water in these water channels have been studied [80,81], and the forces acting on lipids which are pulled out of a membrane have been measured [82]. The bilayer systems themselves are also becoming more complex. Bilayers made of complicated amphiphiles such as unsaturated lipids have been considered [83,84]. The effect of adding cholesterol has been investigated [85,86]. An increasing number of studies are concerned with the important complex of hpid/protein interactions [87-89] and, in particular, with the structure of ion channels [90-92]. 

The regulation of the total peripheral resistance also involves the complex interactions of several mechanisms. These include baroreflexes and sympathetic nervous system activity response to neurohumoral substances and endothelial factors myogenic adjustments at the cellular level, some mediated by ion channels and events at the cellular membrane and intercellular events mediated by receptors and mechanisms for signal transduction. As examples of some of these mechanisms, there are two major neural reflex arcs (Fig. 1). Baroreflexes are derived from high-pressure barorecep-tors in the aortic arch and carotid sinus and low-pressure cardiopulmonary baroreceptors in ventricles and atria. These receptors respond to stretch (high pressure) or... 

For differentiation of G-protein-coupled receptor sub-types from subtypes permanently linked to ion channels (ligand-gated ion channels) the terms metabotropic versus ionotropic receptors, respectively, are used. Prime examples of metabotropic receptors are given by the lnGlu receptor family of G-protein-coupled glutamate receptors. 

Stimulation of mAChRs also results in the activation or inhibition of a large number of ion channels [5]. For example, stimulation of Mi receptors leads to the suppression of the so-called M current, a voltage-dependent Recurrent found in various neuronal tissues. M2 receptors, on the other hand, mediate the opening of cardiac Ikcacii) channels, and both M2 and M4 receptors are linked to the inhibition of voltage-sensitive calcium channels [5]. 

It may be possible to increase the utility of our resources to treat influenza virus infection through combinations of antiviral agents with different modes of action (discussed in Cinatl et al. 2007a De Clercq and Neyts 2007). The sialidase inhibitors, for example, may be able to be used in conjunction with the adamantane-based M2 ion channel inhibitors (Govorkova et al. 2004 Ilyushina et al. 2006), with Ribavirin (Smee et al. 2002) or with non-influenza virus specific therapeutics such as anti-inflammatory drugs (Carter 2007). Combination therapy may also reduce the potential of resistance development (Ilyushina et al. 2006). 

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