Alpha-latrotoxin channels in neuroblastoma cells.
The changes in ionic permeability induced by the application of alpha-latrotoxin to NG108-15 neuroblastoma x glioma cells were examined using the nystatin perforated-patch technique for whole-cell recording. Complex single channel activity appeared in the plasmalemmas after delays that ranged from 1-20 min in Krebs' solution. The conductance of a channel fluctuated among at least three broad, approximately equispaced bands, the maximum conductance being about 300 pS, and the reversal potential approximately 0 mV. The channels were permeable to Na+, K+, Ca2+ and Mg2+, poorly permeable to glucosamineH+ and Cl-, and were blocked by La3+. The channels stayed fully open in Ca(2+)-free solutions with 4 mM Mg2+, in solutions with no divalent cations and in solutions with 2 mM Ca2+ and 96 mM Mg2+. They opened infrequently if both internal and external Cl- were replaced by glutamate-. If alpha-latrotoxin opened similar channels in nerve terminals, the flux of ions through them could account for the massive release of neurotransmitter induced by the toxin.
Hurlbut
W P
WP
Bruno Ceccarelli Center, University of Milan, Italy.
Chieregatti
E
E
Valtorta
F
F
Haimann
C
C
D000818:Animals; D001740:Black Widow Spider; D002118:Calcium / Q000502:physiology; D002463:Cell Membrane Permeability / Q000187:drug effects; D007473:Ion Channels / Q000187:drug effects*; D007811:Lanthanum / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D018000:Receptors, Peptide / Q000502:physiology; D012996:Solutions; D013111:Spider Venoms / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D007473:Ion Channels; D018000:Receptors, Peptide; D012996:Solutions; D013111:Spider Venoms; C034800:alpha-latrotoxin receptor; C020763:alpha-latrotoxin; D007811:Lanthanum; D002118:Calcium