Effects of (+/-)-kavain on voltage-activated inward currents of dorsal root ganglion cells from neonatal rats

Kava pyrones extracted from pepper Piper methysticum are pharmacologically active compounds. Since kava pyrones exhibit anticonvulsive, analgesic and centrally muscle relaxing properties, the influence of a synthetic kava pyr one, (+/-)-kavain, on voltage-dependent ion channel currents was studied. E ffects of (+/-)-kavain on voltage-activated inward currents were analysed i n cultured dorsal root ganglion cells derived from neonatal rats. Voltage-a ctivated Ca2+ and Na+ currents were elicited in the whole-cell configuratio n of the patch clamp technique. Extracellularly applied (+/-)-kavain dissol ved in hydrous salt solutions reduced voltage-activated Ca2+ and Na+ channe l currents within 3-5 min. As the solubility of (+/-)-kavain in hydrous sol utions is low, dimethyl sulfoxide (DMSO) was added to the saline as a solve nt for the drug in most experiments. When (+/-)-kavain was dissolved in DMS O, the drug induced a fast and pronounced reduction of both Ca2+ and Na+ cu rrents, which partly recovered within 2-5 min even in the presence of the d rug. The present study indicates that (+/-)-kavain reduces currents through voltage-activated Na+ and Ca2+ channels. (C) 1999 Elsevier Science B.V./EC NP. All rights reserved.