Key result
Higher NaCl concentration slows tetrodotoxin and saxitoxin binding to canine heart Na channels.
Why the study?
The influence of negative surface charge on toxin binding to canine heart Na channels and its comparison to brain Na channels was not fully characterized.
Negative surface charge is a conserved feature of channel function between canine heart and brain Na channel subtypes, with differences in toxin binding affinities arising from small differences in intrinsic association and dissociation rates.
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May refine cardiac Na channel toxin models; extends brain-heart conservation data but leaves open human translation.
Ravindran et al. (1989) studied this question. Varying [NaCl] concentrations was evaluated on Toxin binding kinetics (association and dissociation rates). The association rate constant of tetrodotoxin and saxitoxin to canine heart Na channels is inversely dependent on [NaCl], revealing a conserved negative surface charge density of 1 e-/400 A2.
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