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 selectivity of omega-CgTx-MVIIC toxin for voltage-dependent calcium currents in cultured myenteric neurons from guinea-pig small intestine. Omega-CgTx-MVIIC (300 nM) blocked 37 +/- 9% of the peak current activated from -80 mV in 15 neurons by mostly affecting the plateau phase of the current. The toxin suppressed peak current activated from -30 mV dose-dependently with an IC50 of 70 +/- 8 nM. The blockade was complete at toxin concentrations of 1 microM. Thus, it appears that omega-CgTx-MVIIC blocks high voltage activated (HVA) calcium channels in the myenteric neurons unselectively as well as other types of HVA Ca2+ channels including P and Q channels.
Department of Physiology, College of Medicine, The Ohio State University, Columbus 43210-1218, USA.
A M
AM
Starodub
J D
JD
Wood
D000818:Animals; D001464:Barium / Q000378:metabolism; D064026:Calbindins; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D020864:Calcium Channels, N-Type; D004553:Electric Conductivity; D006168:Guinea Pigs; D066298:In Vitro Techniques; D020128:Inhibitory Concentration 50; D007421:Intestine, Small / Q000166:cytology / Q000294:innervation; D015640:Ion Channel Gating; D008564:Membrane Potentials; D009197:Myenteric Plexus / Q000166:cytology*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000494:pharmacology*; D064030:S100 Calcium Binding Protein G / Q000032:analysis; D020960:omega-Conotoxins
D001464:Barium; D064026:Calbindins; D002118:Calcium; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D020864:Calcium Channels, N-Type; D010455:Peptides; D064030:S100 Calcium Binding Protein G; D020960:omega-Conotoxins; C053423:Conus magus toxin