Alpha-latrotoxin channels in neuroblastoma cells

• Published in: The Journal of membrane biology Vol. 138; no. 1; p. 91
• Main Authors: Hurlbut, W P, Chieregatti, E, Valtorta, F, Haimann, C
• Format: Journal Article
• Language: English
• Published: United States 01.02.1994
• Subjects: Animals; Black Widow Spider; Calcium - physiology; Cell Membrane Permeability - drug effects; Ion Channels - drug effects; Lanthanum - pharmacology; Membrane Potentials - drug effects; Receptors, Peptide - physiology; Solutions; Spider Venoms - pharmacology; Tumor Cells, Cultured
• ISSN: 0022-2631
• DOI: 10.1007/BF00211072

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.