Inhibitory effects of dihydropyridines on macroscopic K+ currents and on the large-conductance Ca2+-activated K+ channel in cultured cerebellar granule cells

1994 ◽  
Vol 429 (2) ◽  
pp. 176-182 ◽  
Author(s):  
L. Fagni ◽  
J. -L. Bossu ◽  
J. Bockaert
Keyword(s):  
Granule Cells ◽  
Cerebellar Granule Cells ◽  
K Channel ◽  
Inhibitory Effects ◽  
Cerebellar Granule ◽  
K Currents

Appearance of a fast inactivating voltage-dependent K+ currents in developing cerebellar granule cells in vitro

1997 ◽  
Vol 29 (4) ◽  
pp. 291-301 ◽  
Author(s):  
Yoshihiko Wakazono ◽  
Takashi Kurahashi ◽  
Kensuke Nakahira ◽  
Isao Nagata ◽  
Chitoshi Takayama ◽  
...  
Keyword(s):  
Granule Cells ◽  
Cerebellar Granule Cells ◽  
Cerebellar Granule ◽  
Voltage Dependent ◽  
K Currents

scholarly journals Novel K+-channel-blocking toxins from the venom of the scorpion Centruroides limpidus limpidus Karsch

1994 ◽  
Vol 304 (1) ◽  
pp. 51-56 ◽  
Author(s):  
B M Martin ◽  
A N Ramirez ◽  
G B Gurrola ◽  
M Nobile ◽  
G Prestipino ◽  
...  
Keyword(s):  
Primary Structure ◽  
Granule Cells ◽  
Cerebellar Granule Cells ◽  
K Channel ◽  
Amino Acid Residues ◽  
Channel Blocking ◽  
Voltage Dependent ◽  
K Current ◽  
Current Reduction ◽  
K Currents

Two novel toxins were purified from the venom of the Mexican scorpion Centruroides limpidus limpidus, using an immunoassay based on antibodies raised against noxiustoxin (NTX), a known K(+)-channel-blocker-peptide. The primary structure of C. l. limpidus toxin 1 was obtained by Edman degradation and was shown to be composed of 38 amino acid residues, containing six half-cystines. The first 36 residues of C. l. limpidus toxin 2 were also determined. Both toxins are capable of displacing the binding of radio-labelled NTX to rat brain synaptosomes with high affinity (about 100 pM). These toxins are capable of inhibiting transient K(+)-currents (resembling IA-type currents), in cultured rat cerebellar granule cells. About 50% of the peak currents are reduced by application of a 1.5 microM solution of toxins 1 and 2 The K+ current reduction is partially reversible, under washing but not voltage-dependent. Comparison of the primary structure of C. l. limpidus toxin 1 with other known toxins shows 74% identity with margatoxin, 64% with NTX, 51% with kaliotoxin, 39% with iberiotoxin, 37% with charybdotoxin and Lq2, and 29% with leirutoxin 1. The only invariant amino acids in all these toxins are the six cysteines, a glycine in position 26 and two lysines at positions 28 and 33, respectively. The relevance of these differences in terms of possible structure-function relationships is discussed.

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