Spontaneous miniature outward currents in mechanically dissociated rat Meynert neurons

J Physiol. 2001 Jul 1;534(Pt 1):99-107. doi: 10.1111/j.1469-7793.2001.00099.x.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Basal Nucleus of Meynert / cytology
  • Basal Nucleus of Meynert / drug effects
  • Basal Nucleus of Meynert / physiology*
  • Caffeine / pharmacology
  • Calcium / pharmacology
  • Calcium / physiology
  • Electric Conductivity
  • Endoplasmic Reticulum / metabolism
  • In Vitro Techniques
  • Neurons / drug effects
  • Neurons / physiology*
  • Patch-Clamp Techniques
  • Rats
  • Rats, Wistar
  • Ryanodine / pharmacology
  • Sarcoplasmic Reticulum / metabolism


  • Ryanodine
  • Caffeine
  • Calcium