Pharmacokinetic investigation with 125I labeled T-actemodulin (TAM)

The aim of the study was to label TAM with radioactive iodine and to follow its distribution in different organs of rats. T-actemodulin is a thymic hormone isolated from calf thymus by a new technology. TAM was labeled according to the method of Greenwood and Hunter. Two major peaks were observed on the gel chromatography: The first peak contained the labeled TAM; the second peak contained 125I which was not bound to the organic compound. Additional purification of the first peak was performed on a Sephadex G-75 column, and the eluate was designated as purified peak I. After a radioimmune testing it could be concluded that TAM was labeled successfully and the peak I contained 125I-TAM. Peak I, purified peak I and the peak II were applied to young male Wistar rats. The radioactivity of pancreas, kidney, spleen, adrenals, liver, thymus, bone marrow, testis and thyroid were measured after killing the animals 10 min, 60 min, and 24 h after the injections. The pharmacokinetic study showed that all organs, except for the thyroid have a higher affinity for labeled TAM than for the free 125I. Higher accumulation of labeled TAM was observed in the pancreas, kidney, adrenals and spleen. A specific uptake of labeled TAM in these organs can be suggested. Functional interrelations between thymus and pancreas, spleen, adrenals are discussed.