Channel terms

In many neuronal preparations, a significant component of the whole-cell current through Ca channels is resistant to blockade with DHPs, co-conotoxin GVIA, and co-agatoxin IVA (<100 nM), suggesting the presence of a subtype of Ca channel different from L-, N-, and P-types. The isolation, purification, and synthesis of the toxin from the marine snail C. magus co-conotoxin MVllC [16,68] led to the identification and characterization of a new subtype of HVA channel termed Q [80,84]. 

The sum in the right-hand side of (5.48) includes the closed-channel terms, for which E c jx > E, for the reasons given following (5.3). 

When the system moves from left to right on the diagram in Figure 3.8, it is first in the initial state (the channel term U.)> meaning thereby that the electron is localized on A. After this it passes to the adiabatic term (the electron is common to both A and B). Finally, the system goes over to the term of the outgoing channel, i.e. the electron is localized on B. 

Such a pattern (transition from a channel term to an adiabatic term and then to another channel term), however, is not always realized. In order to go over to the adiabatic term, i.e. to modify the electron cloud for a given configuration of nuclei, a certain time is required. 

Collectivization of electrons may occur only in the vicinity of the point of intersection of the channel terms, since it is only at this point that the Franck-Condon principle is satisfied. The fluctuating system moves at a certain velocity. Hence, it may be in the vicinity of the point q only for a certain time If this time is... 

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