Studies on methods for determination of the distribution of cardiac output in the mouse.

Different techniques for determining cardiac output distribution in the mouse have been studied. The soluble indicator technique using injection of rubidium on the right side of the heart was found to give a satisfactory reproducibility which made it possible to determine cardiac output fractions in the normal mouse. The use of radioactivity-labelled microspheres, which must be injected on the side of the heart, was found to give unreliable and non-reproducible results. This was due to difficulty in depositing the microspheres into the left ventricle both when a catheter was inserted via the right carotid artery, or by means of cardiac puncture.