Hallo!

I want to ask about some mini spontaneous currents (less than 50pA) in wholle cell recordings. I made recordings in hippocampal culture, and after block neurotransmission with CNQX-AP5-Bicuculline, some small spontaneous currents keep; what kind of currents could be that, or from where can come this currents?

Thanks.

Histamine, ACh and ATP immediately came to my mind as transmitters that mediate fast neurotransmission (refs below). I'm sure there are more. In right conditions (proximity of postsynaptic receptors etc) they may induce minis.

Yang QZ, Hatton GI.
Histamine mediates fast synaptic inhibition of rat supraoptic oxytocin neurons via chloride conductance activation.
Neuroscience. 1994 Aug;61(4):955-64.

Hatton GI, Yang QZ.
Synaptic potentials mediated by alpha 7 nicotinic acetylcholine receptors in supraoptic nucleus.
J Neurosci. 2002 Jan 1;22(1):29-37.

Jo YH, Schlichter R.
Synaptic corelease of ATP and GABA in cultured spinal neurons.
Nat Neurosci. 1999 Mar;2(3):241-5.