An open welcome: Individual capillaries respond to insulin

Research Areas:

Glucose metabolism, Insulin, Capillary volume, Capillary permeability, Rats

Imaging Needs:

In vivo microscopy

Imaging System:
  • Leica Microsystems intravital microscope
  • 100 W Hg lamp
  • 435 nm band pass interference filter
  • salt water immersion objective lens, NA 0.6
  • Hamamatsu ImagEM C9100 EM-CCD camera
  • Hamamatsu Wasabi software
Imaging the living brain

See how Misha Ahrens, Philipp Keller, and colleagues use lightsheet microscopy to visualize the actions of individual neurons in the whole brain, live and in real time. Read now.


How does insulin keep blood sugar in check?

Insulin regulates blood sugar levels and energy metabolism, notably by increasing glucose uptake in liver, muscle, and fat cells. The hormone also has measureable effects on the kidney, brain, and blood vessels.


To act on body tissues, insulin must reach the microcirculation and pass through the vessel walls into the interstitial space, where it can access insulin receptors on the target cell membranes. Both delivery by the blood and movement through capillary walls may be rate limiting steps in insulin’s actions.

Insulin aids its own distribution by rapidly relaxing arterial muscle and increasing overall capillary blood volume. Previous studies have counted an increase in the number of perfused capillaries. Does insulin increase the volume of individual capillaries as well?


Rapid Insulin-Mediated Increase in Microvascular Glycocalyx Accessibility in Skeletal Muscle May Contribute to Insulin-Mediated Glucose Disposal in Rats
Bart J. M. Eskens, Hans L. Mooij, Jack P. M. Cleutjens, Jozef M. A. Roos, Johanna E. Cobelens, Hans Vink, and Jurgen W. G. E. VanTeeffelen
PLoS One. 2013 8(1): e55399. PMCID: PMC3561231.

By observing individual capillaries in rat skeletal muscle before and during insulin infusion, Eskens et al,1 found an increase in blood volume within minutes of insulin exposure, as reflected in red blood cell column width. Similarly, intravital bright-field video microscopy with a Hamamatsu ImagEM C9100 EM-CCD camera showed a significant rise in capillary tube hematocrit during the first 10 minutes of insulin infusion.

The expansion in capillary volume accompanied an increase in permeability of the glycocalyx – the protective layer of polysaccharides and protein lining the interior of the vessel walls. Insulin’s effects on capillary blood volume, as well as healthy performance on a glucose tolerance test, depended on the presence of intact glycocalyx. The authors conclude that insulin exposure rapidly increases glycocalyx permeability, together with the volume of individual capillaries.


Eskens et al. measured increases in capillary blood volume in vivo using bright-field microscopy and a Hamamatsu ImagEM EM-CCD camera. Recently developed lightsheet microscopy technology using Hamamatsu’s ORCA-Flash4.0 camera enables Misha Ahrens and colleagues to monitor cellular function in the whole brain—read Seeing the Living Brain.


  1. Eskens, et al. Rapid Insulin-Mediated Increase in Microvascular Glycocalyx Accessibility in Skeletal Muscle May Contribute to Insulin-Mediated Glucose Disposal in Rats. PLoS One. 2013 8(1): e55399. PMCID: PMC3561231.
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