Hello everyone
I'm doing evoked EPSC recording in 250µm hippocampal slice, I'm stimulating using a bipolar tungsten electrode from NPI (500µs)
the problem is that I can recruit EPSC but the amplitude will decrease gradually and rapidly so I can't have a stable baseline. I don't think it's a rundown problem since the problem to less degree persist in perforated patch clamp
I'm also recording spontaneous EPSC I can see a lot of them at the start of the exp but once I add GABA(A) and GABA(B) blockers most of those disappears. In my experiment, I'm recording isolated AMPA/NMDA currents
Any insight to help me troubleshoot the problem, I'd greatly appreciate it
My stimulator is an older model of this one https://www.npielectronic.com/product/iso-stim-ii/
and my stim electrode is a Cluster Eletrode, 2-contact IP=2x25um Pt/Ir from FHC positioned at the chaffer collateral close to the CA3 and with moderate distance from the recording electrode
Dear Nour El dine Kassab , 500µs stimulation without any other info, as Max Anstötz pointed out, is complicated to address. However, I'll assume it is a 500µs square pulse. In this case, it is a lot of time stimulating it, I would say. I also record evoked responses, but in the brainstem (MNTB). However, my stimulus duration can be as low as 20µs (100µs would be my max). Another thing to think about: what is the frequency which you are applying these stimulus? 20, 50, 100 Hz? Keep in mind that depending on the synapse you are studying, they don't stand high frequency trains of stimulation (or long ones). If that would be the case, you'd deplete the readily releasable pool of vesicles leading to smaller post synaptic currents, which do recover, but takes time.
If you give us some more details on our protocols, it'll be easier to figure out what may be the issue.
- You use voltage or current to stimulate? And what is the amplitude of the stimulus (in volts or Amps)
-Frequency with which you stimulate.
-For how long you do it.
-If your equipment runs on battery (any part of it), are these batteries trustworthy? This last item is crucial! I had quit some issues with battery-driven stimulation devices already.
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