THE TRANSFER OF POLYSTYRENE MICROSPHERES FROM THE GASTROINTESTINAL-TRACT TO THE CIRCULATION AFTER ORAL-ADMINISTRATION IN THE RAT

Factors relating to the transfer of latex microspheres of 0.87 mu m me an diameter from the gastrointestinal tract (GIT) to the circulation h ave been investigated. The rapidity of appearance and the number of pa rticles increased when the volume of water used as a suspending vehicl e was increased. This was probably due to barrier cell integrity being compromised so that the movement of particles across the enterocytes would be enhanced. Particles were swept into these channels by the wat erflow. The tonicity of the fluid was important as isotonic and hypert onic saline were not as affective as water in transferring particles. Particles were transferred from GIT segments adjacent to the stomach w hich may in part explain the rapid appearance of particles in the circ ulation. Particle uptake was blocked by cytochalasin B which suggests an active component may also be involved.