Can lactate be respired, or must it first be converted to glucose?
You're asking whether milk can be inhaled?
:rofl: No. I suspect s/he's asking about the biochemical pathway of respiration starting with the compound lactate.
I'd answer it, but I'd have to first wake up enough to remember those pathways, or move my butt over to where the books are that might contain that information, and I don't think either is happening tonight. I'm sure someone who can rattle off biochemical pathways in their sleep will be along before I get back to this, but if there's no reply by tomorrow, I'll return to help.
Hmm...I thought I'd do a quick lookup in my old biochem text and give you an answer, but I'm not sure. Yes, there is a respiratory pathway that works via gluconeogenesis starting from lactate, but there's a paragraph commenting on lactate and "new research" which would now be almost 20 years old (it's an old text) that sounds like there could be some other direct pathway, but I have never had an interest in continuing to follow that literature to help with whether something would have been updated on that or not. So, unfortunately, I'm unable to answer this question and will have to defer to someone with more current knowledge in that topic.
The OP may want to look into something called the "lactate shuttle" that has been getting a fair bit of play in the exercise science and physiology crowds. I haven't looked into it beyond the occasional press release, but it appears to be a pathway which functions alongside the gluconeogenesis pathway but distinct from it. Apparently some of the lactate does get oxidized further with this process.
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