S O D I U M A N D

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S O D I U M A N D S O D I U M C H A N N E L
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FUGU

• Its the only delicacy forbidden to be served
• to the Emperor of Japanese
• One of few fish that can close their eyes
• Genome sequenced

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CLINICAL SYMPTOMS
First stage Lip and tongue numbness and tingling
(paresthesias) Facial and extremity
paresthesias Second stage Rapidly ascending
paralysis Nausea and vomiting Final
stage Cardiac dysfunction, CNS dysfunction, and
ultimately respiratory failure
TREATMENT
None no drug that will reverse the effects of
tetrodotoxin poisoning Supportive ABCs Intubate,
IVs to support circulatory collapse, gastric
lavage with charcoal
OUTCOME
50-60 mortality (those who survive do so without
any side effects)
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TETRODOTOXIN
Produced by bacteria Pseudoalteromonas
haloplanktis tetradonis
Concentrated in the liver, gonads, and skin
spines of the fugu through the action of a
specific binding protein
Muscle is free of toxin and can be eaten
Toxin is thermo-stable
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TETRODOTOXIN
All the clinical effects result from blockade of
the voltage gated Na channel
Can not cross the Blood-Brain-Barrier
Affects the brain through a break in the BBB the
area postrema
Neurons directly in the vicinity of the area
postrema are responsible for respiratory
control, cardiovascular tone, consciousness
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tetrodotoxin
Why dont the puffer fish dye from their own
toxin?
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SODIUM HOMEOSTASIS
Complex - controlled primarily by the kidneys and
the CNS
Normal conc. 135 145 mM
Things can wrong and Na conc. can drop well
below normal levels (vomiting) or rise well above
the normal conc. (dehydration)
Goal is to normalize serum Na
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PSYCHOGENIC POLYDIPSIA
Non-physiologic need to drink ? hyponatremia
Serum Na lt 120 mM

Goal is to normalize serum Na
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CENTRAL PONTINE MYELINOLYSIS

Normal Sagital MRI
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