can tetrodotoxin cross the blood-brain barrier? If not, why not?

Question

Serious answers only please

Answer 1

I'd agree that it is unlikely to cross the BBB due to the number of charged group. It is a peptide that contains several amino acids with adequate pKa values to be charged at physiological pH.

It doesn't need to enter cells to have an effect. Its primary mechanism of action is to prevent Na+ ions entering through voltage-gated Na+ channels. Particularly those in neurons. It sits over the pore of the channel which is, of course, extracellular. It needs only to be distributed in the plasma and interstitial space.

Interestingly, many of the VGSCs in the dorsal root ganglia are TTX-resistant.

Answer 2

"tetrodotoxin cannot cross the blood brain barrier or the nerve membrane because it is a charged molecule with an amine group and several hydroxyl groups."

Answer 3

pretty much sure it can, either by osmosis, or respiration. Look into the link below as the process seems a bit more complicated than just fluid and gases exchanges ...