I work with mouse models of duchenne muscular dystrophy and often find that I have more difficulty in obtaining a good VC occlusion in these mice. By 'good' I mean that the loops move in a downwards slope from right to left. Sometimes, in the DMD animals I find that my loops move downwards from left to right and therefore I cannot generate contractility data. Can anyone tell me a way of remedying this or why this might occur?
When you perform IVC occlusion you have to be careful to occlude only the inferior vena cava to get reliable results. Most likely you are performing an external occlusion therefore you are not sure that you are occluding the IVC only. It is possible that you, in order to occlude the IVC, are squeezing the liver or highly probable you are applying a certain pressure to the aorta, therefore your PV loops look like a halfway beween IVC occlusion and aortic arch occlusion. Doing so, you have artefactual data because you reduce the preload (the reason of IVC occluson) but also increase to a certain degree the afterload.
To have clean and reliable data you should perform an internal IVC occlusion. Open the abdomen , visualize the IVC and then occlude directly the IVC above the kidney in order to avoid the blood from the renal artery.you should get "better" occlusion and more reliable data.
Hi Antonio. I perform an internal IVC however, my experimental setup does not allow me to have a clear view of the vessel so it is probable that I may occlude something else in addition. Thanks!
Any tips for visualising more clearly the IVC appreciated! I usually take care to not put pressure on the liver but I often feel that I have to 'root around' in order to find the IVC and occlude it.
If you cannot visualize the IVC is difficult. To better visualize he IVC ou should open the abdomen and try to move the gut aside with some cotton tip applicator in order to avoid the damage of the vessel.then you will find the renal vein and you can proceed from that.
However, if you are unable o visualize the IVC, you can play some tricks. One is to gently move the liver upwards and occlude just below the liver. Otherwise you can visualize the kidney and occlude few millimeters inward the renal vein.
Let me know if these works.
Hi Antonio. I usually occlude just below the liver as you describe. What puzzles me is why the loops might move to the right in one particular mouse strain- i.e the cardiomyopathic mice.
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