Transport of K 42+ , Na 24+ , and I 131 + by the Pulmonary Circulation

Abstract

The transport of K⁴²⁺, Na²⁴⁺, and I¹³¹⁺ by blood through the heart and lungs in the canine heart-lung preparation was studied. Simultaneous injection of each tracer was performed together with nondiffusible Risa as a reference label. The data show that in a single passage through the lung, a fraction of the injected radioactive electrolyte moves out from the blood and partially returns. This alters the shapes of the dilution curves and the results of cardiac output and central volume calculations. The implications of these findings in the suggested use of radioactive electrolytes for the application of the Stew art-Hamilton method in human and animal investigations is discussed. The possibility is suggested that in the Starling preparation, the difference in flows calculated from the extrapolated and complete dilution curves of a non-diffusible tracer may he related to the coronary flow.