I couldn't go to the bees today...had to teach.  A few encouragements came my way.  So....

Randy said:

"If such opening of the channels were irreversible, then the sodium channels
would remain open, and be cumulative, as you suggested when you started
this discussion, citing Haber's Law.  Now you appear to be taking the
reverse argument."

Here is a "teachable moment".  The neuron is basically a battery.  If you aggressively discharge your battery, it wears out and is dead.  Same with neurons.  Batteries recharge if energy is applied.  Same with neurons.  They have sodium-potassium pumps which work to recharge (re-establish the negative resting potential) of the neuron.  The blocked AChR channels can be open and leak, and the Na-K pumps oppose the leak by moving the ions back out of the cytosol.  They are very efficient at this and under normal conditions can re-establish the resting potential in fractions of a second.

The reason nicotine doesn't kill you at sublethal (smoker) levels is the same reason neonics *or any other pesticides that target the AChR receptors as agonists* don't kill insects at sublethal levels...the amount of leak isn't great enough to completely discharge the neuron battery because the Na-K pumps can sort of keep up with it (although they don't do it perfectly so the correct resting potential is not achieved).  Because there is inadequate recovery when the membrane is sufficiently leaky, the neuron becomes more excitable, which is partly why people become addicted to nicotine *at sublethal doses*.  Nicotine is indeed very toxic once you consume enough to bind all the AChR and completely depolarize your neurons...then you die, just like the bugs.

Consider this.  Nicotine (an AChR agonist) in human smokers dulls the senses of taste and smell...these senses are functions of the nervous system.  Would AChR agonists have that effect on bees?  Impair their sense of smell? What do you think that means to foraging, and queen/worker/brood interactions?  Or housekeeping work, like dumping bad brood, or disposing of other noxious stuff?  I think it's worth pondering.

Christina

P.S.  Randy, please re-read what I was saying when I brought up Haber's Law.  I think you misunderstand what I was trying to convey.

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