IDENTIFICATION OF BETA-ADRENOCEPTORS IN RAT LYMPH-NODES AND SPLEEN - AN AUTORADIOGRAPHIC STUDY

The anatomical localization of beta(1) and beta(2)-adrenoceptors was s tudied in rat lymphoid tissues by quantitative autoradiography using [ I-125]cyanopindolol as a ligand. In lymph nodes, a significant density of these receptors was found in the medullary cords and the interfoll icular cortex, while only low densities were observed in the paracorte x. No detectable binding appeared in the remaining areas. In the splee n, these receptors were mainly localized in the capsule, marginal zone of white pulp and red pulp, while the labelling over the white pulp w as extremely low. The subtype beta(2) was predominant in both lymph no des and spleen. The results suggest that beta-adrenoceptors are presen t in mature cells in lymphoid tissues and are probably not involved in homing mechanisms.