Black widow spider
Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Abstract The changes in ionic permeability induced by the application of α-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 Ca2+-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 α-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.
Type of Medium: