Dr. Michael Ormsbee

So then the needle is out entirely. You just leave this little flexible tubing under the skin. Luckily now they make these as concentric probes. So it's only one poke instead of two. So you'd only have to pinch and put one poke in there. And then what happens is there's an inlet tube and an outlet tube, tiny little micro tubes. And then you can say – you can perfuse all kinds of stuff.

So then the needle is out entirely. You just leave this little flexible tubing under the skin. Luckily now they make these as concentric probes. So it's only one poke instead of two. So you'd only have to pinch and put one poke in there. And then what happens is there's an inlet tube and an outlet tube, tiny little micro tubes. And then you can say – you can perfuse all kinds of stuff.

But we perfuse saline and saline goes into the interstitial space and mixes around and then comes out the outlet tube. So what I measure should be saline plus whatever is coming out of the cells around the probe. And so we measure in that probe real time all kinds of stuff. But traditionally, glycerol is the primary marker we're looking at for fat metabolism, so specifically lipolysis.

But we perfuse saline and saline goes into the interstitial space and mixes around and then comes out the outlet tube. So what I measure should be saline plus whatever is coming out of the cells around the probe. And so we measure in that probe real time all kinds of stuff. But traditionally, glycerol is the primary marker we're looking at for fat metabolism, so specifically lipolysis.

Yeah, but slightly different. So the oxidation piece is a little bit different. We're looking specifically at lipolysis. We have no idea... if it's actually being burned, it's just being liberated from the cell. And so we'll pick that up in the probe and we have to measure that. So adipocytes lack the enzyme glycerol kinase and so glycerol can't go back into the adipocyte.

Yeah, but slightly different. So the oxidation piece is a little bit different. We're looking specifically at lipolysis. We have no idea... if it's actually being burned, it's just being liberated from the cell. And so we'll pick that up in the probe and we have to measure that. So adipocytes lack the enzyme glycerol kinase and so glycerol can't go back into the adipocyte.

And so it is a little more stable than measuring free fatty acids, for example, because they can a little more readily go in and out of the fat cell in certain conditions. So glycerol is the main marker of lipolysis.

And so it is a little more stable than measuring free fatty acids, for example, because they can a little more readily go in and out of the fat cell in certain conditions. So glycerol is the main marker of lipolysis.

Right. So you've heard of a triglyceride. Everybody's probably heard of that. So the backbone of a triglyceride, tri being three, are three fatty acids attached to a glycerol. And so that's liberated through hormone-sensitive lipase as the adipocyte is stimulated to release fat. And that can be from all kinds of stuff, but exercise is typically what we use to drive that.

Right. So you've heard of a triglyceride. Everybody's probably heard of that. So the backbone of a triglyceride, tri being three, are three fatty acids attached to a glycerol. And so that's liberated through hormone-sensitive lipase as the adipocyte is stimulated to release fat. And that can be from all kinds of stuff, but exercise is typically what we use to drive that.

And then they'll all be liberated from the cell, and eventually glycerol will be also put into the intersocial space. And ultimately, we can pick that up in the microdialysis dialysate that we collect.

And then they'll all be liberated from the cell, and eventually glycerol will be also put into the intersocial space. And ultimately, we can pick that up in the microdialysis dialysate that we collect.

Yeah, and what's nice about this technique is that we're describing it in the abdominal fat tissue. Yeah, it's where people care. But we also can do it right now, like we're running a study where we're looking at the abdominal and we're also looking at the gluteal. And men and women have different amounts of fat in those areas.

Yeah, and what's nice about this technique is that we're describing it in the abdominal fat tissue. Yeah, it's where people care. But we also can do it right now, like we're running a study where we're looking at the abdominal and we're also looking at the gluteal. And men and women have different amounts of fat in those areas.

And it all has to do with the receptor type that's on the adipocyte in that space. And so we have like these beta and these alpha receptors that primarily drive what's going on in these different spaces. So you and I will have a different concentration of the alpha and beta receptors on the adipocyte in our abdomens versus our hips and top of our buttocks, right?

And it all has to do with the receptor type that's on the adipocyte in that space. And so we have like these beta and these alpha receptors that primarily drive what's going on in these different spaces. So you and I will have a different concentration of the alpha and beta receptors on the adipocyte in our abdomens versus our hips and top of our buttocks, right?

And so women will also have a different profile. And that also changes to like, for example, the perimenopause-menopause transition. A lot of those things are different.

And so women will also have a different profile. And that also changes to like, for example, the perimenopause-menopause transition. A lot of those things are different.

really interesting for people to know like what's going on in these different tissues can we fix it and then we can also put drugs through the probe if we need to and we can stimulate or inhibit those receptors and figure out mechanistically what's going on in the different tissues but for our pre-sleep feeding studies we weren't perfusing any drugs.

really interesting for people to know like what's going on in these different tissues can we fix it and then we can also put drugs through the probe if we need to and we can stimulate or inhibit those receptors and figure out mechanistically what's going on in the different tissues but for our pre-sleep feeding studies we weren't perfusing any drugs.