The double-ticker: an improved fast drug-application system reveals desensitization of the glutamate channel from a closed state.
The present study describes a modification of the fast drug-application technique (ticker) which combines two fast-application systems, 'the double-ticker'. With the double-ticker, drugs can be applied to excised patches from either one of the tickers permitting switching among three different solutions in the sub-millisecond range. We made use of this advantageous feature of the double-ticker to study two aspects of the glutamate receptor channel in crayfish muscle. The first concerns revealing the number of glutamate binding sites from measurements of a dose-response relation (2-3 sites). The other relates to the state from which the receptor undergoes desensitization. For the quisqualate-sensitive glutamate receptor desensitization occurs from a closed state. This is in addition to desensitization from an open state.
Otto Loewi Center for Cellular and Molecular Neurobiology, Hebrew University, Jerusalem, Israel.
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D000818:Animals; D003400:Astacoidea; D018698:Glutamic Acid / Q000494:pharmacology; D007473:Ion Channels / Q000502:physiology*; D018408:Patch-Clamp Techniques; D017470:Receptors, Glutamate / Q000502:physiology*; D013997:Time Factors
D007473:Ion Channels; D017470:Receptors, Glutamate; D018698:Glutamic Acid