Pressure Fixation of Isolated Murine Pulmonary Valve: A Procedure to Isolate and Chemically Fix the Mouse Pulmonary Valve in Closed Conformation

To begin, secure a euthanized mouse in the supine position. Incise laterally through the thoracic wall to access the thoracic cavity and expose the heart. Excise the right atrium and inject saline into the left ventricle to drain blood from the heart.

Sever the vascular connections by cutting off the major blood vessels. Further, incise the pulmonary artery at a suitable distance from the ventriculo-arterial junction, which serves as the conduit for pressurization. Remove the ventricles to expose the ventricular side to atmospheric pressure.

Now, secure a pressurization tubing into the pulmonary artery, ensuring adequate clearance between the ventriculo-arterial junction and the tubing end to allow valve leaflets to move during pressurization.

To the tubing, connect the saline-filled reservoir fixed to a calculated height relative to the pulmonary valve based on the desired hydrostatic pressure to be applied to the arterial side of the valve. The unidirectional flow from the arterial side with the applied hydrostatic pressure results in closure of the valve leaflets and distention of the pulmonary trunk.

Subsequently, introduce a suitable fixative into the reservoir and continue the perfusion. The perfused fixative stabilizes cellular morphology and tissue architecture. 

Place a fixative-soaked gauze over the tissue to fix the tissue surrounding the valve and prevent drying. Store the fixed heart valve in fixative until use.