Tetrodotoxin (citrate free)

Potent, selective and reversible, voltage dependent Na⁺ channel blocker. Use dependent. Commonly used in electrophysiological preparations to block or reduce excitability. Water soluble, Tetrodotoxin citrate also available.

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.