Abstract
The lymph nodes are known to trap with foreign particles, such as perfluorocarbon emulsions, liposomes, carbon particles and tin colloid. For this reason, these particles are used as tracer and vehicle of drugs which target the lymph nodes. Little information, however, exists regarding barrier function of the lymph nodes. Thus, in this study, we have attempted to develop new animal model for evaluating barrier mechanisms through the lymph node. Male Japan White rabbits were anesthetized with ketamine chloride (20 mg/kg iv.) and pentobarbital sodium (20 mg/kg iv.). Centripetal and retrograde cannulations were performed in one of the popliteal afferent and efferent lymph vessels, respectively. All other efferent lymphatics were ligated completely. Fluorescently labeled latex microspheres (0.2–2.0 μm in diameter) were administered into the afferent lymph vessel. Then, changes in concentration of the microspheres in the efferent lymph vessel were determined by measuring the number of the particles under a fluorescent microscope. Several percent of the microspheres with 0.2 μm in diameter was appeared in the efferent lymph by 30 min after the administration. No microsphere with 2.0 μm in diameter was observed in the efferent lymph by 120 min after the administration. These results strongly suggest that size-dependent barrier mechanisms exist in the lymph node. [Jpn J Physiol 55 Suppl:S94 (2005)]
