Tetrodotoxin (citrate free)

Tetrodotoxin is commonly used in electrophysiology to block excitability by inhibiting action potential firing within neurons. It is commonly applied at concentrations of 1 μM. Tetrodotoxin from Hello Bio works as expected and blocks action potential firing (see Fig 1 and 2 above).

 #Protocol 1: Effect of TTX citrate on action potentials in mouse cortical neurons

• Whole cell voltage clamp recordings were obtained from layer V pyramidal neurons of the mouse prelimbic cortex brain slice.
• Neurons were held at the resting membrane potential (~ -70 mV) and injected with a 500 pA 300 ms current step to induce action potential firing.
• TTX was bath applied for 10 min first at 100 nM then 300 nM, 1 μM and 2 μM. After each drug application a current step was recorded to assess action potential blockade.

#Protocol 2: Effect of TTX citrate on EPSPs and action potential firing in mouse cortical neurons

• Whole cell voltage clamp recordings were obtained from layer V pyramidal neurons of the mouse prelimbic cortex brain slice.
• Neurons were held at the resting membrane potential (~ -70 mV) and EPSP were evoked by placing a stimulating electrode close to the recorded the neuron in layer II/III.
• EPSPs and action potentials were evoked by single square (150 μs) pulse every 10 sec with an intensity that produced both an EPSP and action potential.
• TTX was bath applied for 10 min first at 100 nM then 300 nM, 1 μM and 2 μM whist continually evoking and recording EPSP/A.Ps.