Dendrotoxin and charybdotoxin increase the cytosolic concentration of free Ca2+ in cerebrocortical synaptosomes: An effect not shared by apamin

FEBS Letters

Dolly, J.Oliver²  Tibbs, Gareth R.²  Nicholls, David G.¹ 

[1] Department of Biochemistry, University of Dundee, Dundee, Scotland;Department of Biochemistry, Imperial College of Science and Technology, London SW7 2AZ, England

关键词: Dendrotoxin;    Charybdotoxin;    Apamin;    K+ channel;    Ca2+;    cytosolic free fraction;    Nerve terminal;    4-AP;    4-aminopyridine;    DTX;    dendrotoxin;    CTX;    charybdotoxin;    fura-2/AM;    fura-2 acetoxymethyl ester;    Tes;    2-([2-hydroxy-1;    1-bis(hydroxymethyl)-ethyl]-amino)-ethane sulphonate;    [Ca2+]c;    cytosolic free Ca2+ concentration;    CNS;    central nervous system;    PNS;    peripheral nervous system;   

DOI  :  10.1016/0014-5793(89)81081-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Nanomolar concentrations of charybdotoxin or dendrotoxin increase the cytoplasmic free Ca²⁺ concentration in isolated central nerve terminals. The effects of the two toxins, normally considered to be blockers of K⁺ channels controlled by voltage in a Ca²⁺ -sensitive or -insensitive manner, respectively, show only marginal additivity. Apamin, an inhibitor of low conductance Ca²⁺ -activated K⁺ channels, was without effect in either the absence or presence of dendrotoxin. The effect of charybdotoxin on polarized, isolated central nerve terminals seems to be mediated largely by a block of K⁺ channels sensitive to dendrotoxin. Apparently, these voltage-operated K⁺ channels make a more significant contribution to maintaining the polarized potential of synaptosomes than do those activated by Ca²⁺.

【 授权许可】

Unknown