Dehydration in the brain

One of the very cool opportunities from being in the Lower 48 was being invited to spend time with the Baen Barflies at DragonCon. Now, I've heard of Baen's Bar from a good friend and for the last twelve years, but somehow I never quite got 'round to joining - especially when he told me the good stories anyway. This includes moments like watching Mad Mike (Michael Z Williamson, whose books are as great reads as they are politically incorrect) make a drink called "clubbed seal" (and failing to get up off the couch afterward. Tasty and potent!)

It also included meeting Speaker To Lab Rats, who is a real live neuroscientist, and a really great guy. He is not only gracious and generous, he also has a wickedly keen wit and isn't afraid to use it. He keeps a blog that puts mine to shame:Teddy's Rat Lab, which explains very interesting science in ways that let laymen understand.

I was reading the second of his two-part series on Diabetes in the brain, on diabetic neuropathy, and experienced on of those moments in which the perfectly well-put fact suddenly acts like a seed in a supersaturated solution, making fuzzy generalizations, "everybody knows" and "the symptoms are" resolve into a perfectly understandable cause and effect.

As previously mentioned, neurons in the brain are not dependent on insulin for their uptake of glucose from the blood. This is not to say that neurons are insensitive to insulin or that insulin has no effect on neurons...

Thus, in the brain the effects of high blood glucose are largely due to the osmotic properties of the glucose molecule dissolved in the liquid component of blood. In this manner, glucose acts very much like high salt concentrations. It is fairly well known that one means of preserving food is to dehydrate it, quite frequently with salt.

I love learning things. Especially things that help me understand how the world works, and make sense out of the universe. So I dashed downstairs, and excitedly related this to Calmer Half. "So, it's actually the dehydration of nerve cells that poisons and kills them, which is why diabetics end up having problems with vision and feeling in their feet! Isn't that cool?"

Calmer Half, who is still having struggles aplenty with the low-carb diet and blood sugar, didn't look so calm as I name him. In fact, he looked at me with the same face a soldier on patrol turns toward the approaching sandstorm. "No. It's not." He frowned, and it was a frown that made me decide that maybe I better take myself off somewhere else and remove my feet from my mouth.

...And for some reason, the usual sources of carbalicious temptation just weren't as appealing that night.