The isolated perfused ''working'' rat heart: A new method

This paper presents a ''working'' isolated perfused rat heart. A special double cannula was designed consisting of an outer cannula that is inserted in the aorta and an inner cannula that is advanced into the left ventricle. The perfusion fluid flows through the inner cannula into the left ventricle, and is ejected from there into the aorta. If the outer cannula system is closed, the fluid perfuses the coronary vessels and drips off outside the heart. When the outer cannula is open and certain pressure resistance is applied, a fraction of the ejected fluid perfuses coronary vessels and the rest is expelled. Because the inner cannula can easily be retracted into the outer cannula, which is placed in the aorta, this preparation provides an opportunity to use the same heart as a ''working'' or ''non-working'' model for investigating functions of the heart. The effects of epinephrine and yohimbine were tested on this model. This preparation is simple, durable, and reliable.