Ion channel conductivity

Perturbation of ion channel conductance alters the hypnotic response to the (Xj-adrenergic agonist dexmedetomidine in the LC of the rat. Anesthesiology 81 1527-1534. 

Another way to assess ion channel conductance is to use artificial phospholipid vesicles (liposomes) as cell models. These structures (described in more detail in the next chapter) are commonly used to transport vaccines, drugs, enzymes, or other substances to target cells or organs. The vesicles, which are several hundred nanometres in diameter, do not suffer from interference from residual natural ion channel peptides or ionophores, unlike purified natural cells. A liposome model was used to test the ion transport behaviour of the redox-active hydraphile 12.36. The compound transports Na+ and the process can also be monitored using 23Na NMR spectroscopy.26 The presence of the ferrocene-derived group in the central relay allows the ion transport to be redox-controlled - oxidation to ferrocinium completely prevents Na+ transport for electrostatic reasons. Some representative data from a planar bilayer measurement is shown for hydraphile 12.36 in Figure 12.16. 

Smart, O. S., Breed, J., Smith, G. R., and Sansom, M. S. (1997). A novel method for structure-based prediction of ion channel conductance properties. Biophys. J. 72, 1109-1126. 

GABA is the main inhibitory transmitter in the CNS. Two GABA molecules are required to increase Cf ion channel conductance (by increasing the time the channel is open). This reduces the likelihood of an action potential. 

All electrophysiological techniques that are used to study ion channel activity are based on the fact that ion channels conduct electrical current carried by ions (Section 16.2) that can be detected "with highly sensitive electronic equipment. 

The molecular mechanism operative in the change in ion channel conductances is not yet clearly understood. However, it is likely that these ion channels are composed of lipid-protein complexes. There are at least two theories for the opening of the sodium channel (1) Voltage-dependent ion channel conductance When the depolarization potential is greater than the threshold value, the sodium channel opens. (2) Ca " removal from the membrane outer surface (probably, from the outer part of the sodium channel) Such removal acts as a trigger for opening the sodium channel. It seems... 

It was from studies and conclusions based upon the classical work of Hodgkin and Huxley (1952) that provides us with a basis for a mathematical description of voltage-dependent ion channel conductance. Their experimental strategy was... 

IV. Oxygen Sensor and Ion Channel Conductivity A. Cytochrome c Oxidase... 

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