Preparation of radioactive bromamine-T by isotope exchange with radioactive bromine

In hearts of mice the accumulation of 15-/para-¹²³I-phenyl/-pentadecanoic acid /IPPA/ was determined 3 min after injection under different conditions. Using propionate as an agent competing with the albumin binding sites for fatty acids, the concentration of free fatty acids was increased in the circulating blood and the myocardial uptake of IPPA rose from 38.8±3.7% inj. dose/g under normal conditions to 46.2±5.1% inj. dose/g. On the other hand, the addition of 2-Br-palmitic acid reduced the myocardial uptake to a value of 31.0±2.5 inj. dose/g due to the known effect of blocking the transport of fatty acids into the cells. The results suggest the existence of a carrier-mediated transport process of fatty acids into the myocardial tissue.