Abstract: The aim of this study was to explore whether it is possible to perfuse the isolated rat heart through a needle inserted into the left ventricle through the apex of the heart and determine the cardiac rhythm of such preparation. The heart was excised and the perfusion started via the aorta. Then a needle was inserted into the left ventricle via the apex of the heart through which the perfusion solution is pumped. If the aortic column is closed, all the perfusion solution passes the coronary vascular bed. If the aortic column is open, the afterload could be set by adjusting the height of the fluid in the aortic column above the heart. Drugs were given via an in-line injection port placed at the perfusion line. ECG and aortic pressure in the aortic cannula were recorded. Heart rhythm and rate remained stable when the heart was perfused for 2 h at the afterload of 55 mm Hg, at the pump rate of 40 mm min 1. The initial heart rate was 250+/-23 beats min 1 and after 2 h it was 238+/-27 (n = 7). Epinephrine induced transitory tachycardia. Oxotremorine (50 ng) caused transient cardiac arrest, while 250 ng of this agent caused ventricular fibrillation. Glycopyrrolate prevented the effect of oxotremorine. The insertion of a needle did not cause significant damage of the heart with this technique. The preparation is stable for more than 2 h. The preparation is suitable for study of drug effects on the heart, especially heart rate and dysrhythmias.
Bozana Alexander , Malini Rao , Rajko Igic and Sanja Milutinovic , 2007. New Variant of the Isolated Perfused "Working" Rat Heart. Research Journal of Pharmacology, 1: 1-4.