Accelerated communication - Selectivity of omega-CgTx-MVIIC toxin from Conus magus on calcium currents in enteric neurons

Whole-cell perforated patch clamp recordings were used to analyze selectivi ty of omega-CgTx-MVIIC toxin for voltage-dependent calcium currents in cult ured myenteric neurons from guinea-pig small intestine. omega-CgTx-MVIIC (3 00 nM) blocked 37 +/- 9% of the peak current activated from -80 mV in 15 ne urons by mostly affecting the plateau phase of the current. The toxin suppr essed peak current activated from -30 mV dose-dependently with an IC50 of 7 0 +/- 8 nM. The blockade was complete at toxin concentrations of 1 mu M Thu s, it appears that omega-CgTx-MVIIC blocks high voltage activated (HVA) cal cium channels in the myenteric neurons unselectively as well as other types of HVA Ca2+ channels including P and Q channels. (C) 1999 Elsevier Science Inc.