Hi everyone,
I am operating mice to induce ischemia in the left hindlimb by ligating the femoral artery. The procedure is well established i our laboratory and after three years of working on the project I might say we got quite experienced with it.
However, recently we see that mice of one certain genotype develop swelling of the right (=not operated) hindlimb. Infection is not likely, as the rest of the mice (operate leg, eyes, etc) are not inflammated, red, or swollen...
Does anyone has an idea what might be the reason of this swelling?
Very interesting, if you are not making an incision in the contralateral side I really do not see why they would be experiencing any sort of swelling. Make sure that somehow during the procedure the leg is not being injured unintentionally. If they are guarding the injured side and not bearing weight on it you could argue that they are experiencing the contralateral swelling due to overload but it would be strange to only see it in a specific strain. Unless your mice have some sort of genotype-associated vascular, muscular or lymphatic deficiencies I find it difficult to explain.
Do you tape the feet down to operate, maybe they react to something in that? Or perhaps inflammation to the de-hairing? Alternatively they might get ROS from the Laser if you do LDPI? Something must have happened to the contralateral feet.
Otherwise you get into explanations of flow shunting from the aorta to only one femoral artery, which might do stuff.
The contralateral leg should have intact function of flow regulation, such as myogenic response of vascular smooth muscle for pressure balance. The swelling suggests vasodilation of the leg. Maybe the ischemic leg is dumping metabolites into the circulation system or causing systemic inflammation, which induces vasodilation of the control leg. Another possible cause is (para-)/sympathetic nervous system, assuming that ligation does not cut off signal transduction of nervous system? What exactly is the different genotype?
Bart,
Perhaps the ligation of the left femoral artery is causing a blood clot to form near the ligation. The clot may be released and flushed into the common iliac artery or aorta and into the right femoral artery. This could occur during the surgery (since blood flow in the right femoral is maintained during surgery) or just after the ligation is released. Such a clot would cause an obstruction in the blood flow and swelling in the affected limb. Don't know why this would be genotype related.
Dear all,
Thank you so much for your thoughts!
We are using the method as described in the following article:
http://www.jove.com/video/1035/murine-model-of-hindlimb-ischemia
It happens in a wild type and a knock out stain both generated with a mixture of 129Sv, C57BL6J, and mdx-wild type mice.
Indeed, the idea that we accidentally injure the leg was our first thought - we indeed use leukoplast-like tape to tie the legs down... however, wouldn't we than see swelling in both legs?
The idea of vasolidation and the blood clot - hypotheses sound the most likely to us...
We have repeated our experiments, and in the latest repetition we found much less cases of swelling (approx. 20% in first, and apporx 5% in new experiment)...