title: Spontaneous miniature outward currents in mechanically dissociated rat Meynert neurons.
abstract: 1. Spontaneous miniature outward currents (SMOCs) were observed in mechanically dissociated rat Meynert neurons using nystatin perforated patch recordings under voltage-clamp conditions. 2. SMOCs were blocked by apamin, a selective blocker of small conductance Ca(2+)-activated K(+) (SK) channels, but not by blockers for other types of Ca(2+)-activated K(+) channel. 3. Ryanodine (10-100 microM) reduced both the amplitude and frequency of SMOCs. Caffeine (1 mM) increased the SMOC frequency. Blockers of the sarco/endoplasmic reticulum Ca(2+)-ATPase completely abolished SMOCs, indicating a requirement for functioning sarco/endoplasmic reticulum (SR/ER) Ca(2+) stores. 4. Both Cd(2+)-containing and Ca(2+)-free solutions partially inhibited SMOC frequency, a result which suggests that Ca(2+) influx contributes to, but is not essential for, SMOC generation. 5. Thus, SMOCs are SK currents linked to ryanodine- and caffeine-sensitive SR/ER Ca(2+) stores, and are only indirectly influenced by extracellular Ca(2+) influx. The development of this new, minimally invasive mechanical dissociation method has revealed that SMOCs are common in native CNS neurons.
authors: Cellular and System Physiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
authors: J
authors: J
authors: Arima
authors: N
authors: N
authors: Matsumoto
authors: K
authors: K
authors: Kishimoto
authors: N
authors: N
authors: Akaike
mesh_terms: D000818:Animals; D020532:Basal Nucleus of Meynert / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology / Q000502:physiology; D004553:Electric Conductivity; D004721:Endoplasmic Reticulum / Q000378:metabolism; D066298:In Vitro Techniques; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D012433:Ryanodine / Q000494:pharmacology; D012519:Sarcoplasmic Reticulum / Q000378:metabolism
chemical_list: D012433:Ryanodine; D002110:Caffeine; D002118:Calcium