A device for recording left ventricular contraction and electrocardiogram in nonworking isolated perfused rat heart

Using the isolated Langendorff rat heart preparation perfused at a constant flow rate (about 6 ml.min-1 pro heart) with a modified Krebs-Henseleit solution, methods for recording left ventricular cavity pressure and electrocardiogram (ECG) changes were devised. Stable levels of mechanical activities were reached 60--90 min after start of perfusion and were maintained for at least 4 hr. When either norepinephrine (0.05--0.15 microgram) was injected into the aortic bulb of the heart, sensitive changes in the measurable cardiac parameters were observed and changes in ECG patterns were particularly characteristic. Our results indicate that this experimental model may be useful for evaluating numerous functions of the isolated heart.