Materials
Nicotine hydrogen tartrate salt (nicotine),nitrendipine,verapamil,ω-agatoxin
IVA, cadmium chloride, dimethylsulfoxide (DMSO) were obtained from
Sigma Aldrich (St. Louis, MO, USA). Dihydro-β-erythroidine hydrobromide
(DHβE)
(TOCRIS, Bristol, UK), µ-conotoxinGIIIB (Peptide institute Inc., Osaka,
Japan). Drugs were dissolved in distilled water with the exceptions of
nitrendipine and verapamil which were dissolved in DMSO. Further
dilutions for all drugs were done in Ringer solution. In experiments
with drugs which were dissolved in DMSO, the same concentration of DMSO
was added to the control solution as was present in the solution with
the agent. Finally, the DMSO concentration in the solution did not
exceed 0.01%.