M-type K+ current inhibition by a toxin fron the scorpion Buthus eupeus.
A number of invertebrate venoms have been tested for effects on M-type K+ currents (IK(M)) in differentiated mouse neuroblastoma X rat glioma NG108-15 cells. Among the venoms tested, Buthus eupeus scorpion venom reversibly inhibited IK(M) by approximately 44% at 50 microgram/ml. Inhibition was not due to activation of bradykinin or nucleotide (pyrimidine) receptors. On venom fractionation, a polypeptide of 4 kDa was purified that inhibited IK(M) by approximately 45% with an IC50 of approximately 33 nM. Neither the crude venom nor the purified polypeptide affected the Ca2+ current or the delayed rectifier K+ current. While the crude venom prolonged the Na+ current, the polypeptide did not. Thus, the 4 kDa Buthus eupeus polypeptide appears to be a selective inhibitor of IK(M) in NG108-15 cells.
Filippov
A K
AK
Department of Pharmacology, University College London, UK.
Kozlov
S A
SA
Pluzhnikov
K A
KA
Grishin
E V
EV
Brown
D A
DA
D000818:Animals; D002454:Cell Differentiation; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D005910:Glioma / Q000473:pathology; D006822:Hybrid Cells; D008564:Membrane Potentials; D051379:Mice; D009447:Neuroblastoma / Q000473:pathology; D015221:Potassium Channels / Q000187:drug effects*; D051381:Rats; D012604:Scorpion Venoms / Q000737:chemistry* / Q000494:pharmacology*; D014118:Toxins, Biological / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D014688:Venoms / Q000494:pharmacology
D015221:Potassium Channels; D012604:Scorpion Venoms; D014118:Toxins, Biological; D014688:Venoms