I was hoping that someone might have an answer that one of my colleagues is seeing during their rat perfusions. They have noticed that rats are making considerable movements during saline rinse. This is influencing the quality of perfusion with paraformaldehyde as the animals no longer make any movements and brain tissue (which we are interested in) appears quite soft. The issue is definitely not related to anesthetic as the animals are well over-dosed at this point and have all shown stage III anesthesia (we aren't barbaric here). Rats are initially intracardially perfused with 0.9% physiological saline (dissolved dH2O) to washout blood, followed by 4% paraformaldehyde (dissolved in 0.1 M PB) to fix tissue. Needle is placed in the ascending aorta or left ventricle and the heart clamped to keep needle in place, the right atrium is clipped. I have only two ideas regarding what the problem could be 1) related to salt content of the saline; or 2) some how the students are mispositioning the placement of the perfusion needle?
Does anyone have an idea regarding what the problem could be? Has anyone seen this before?
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