Transperitoneal transport of methotrexate in vitro

The study presents estimation of bidirectional transport of methotrexate (MTX) across rabbit's parietal peritoneum in vitro. The experiments were done under iso- and hyperosmotic conditions. In the former case the amount of MTX transported transperitoneally from vascular to mesothelial side of the membrane was higher than that transferred to opposite direction, the values of the transport to both directions were observed to decrease with time. Change of the medium from isoosmolarity to hyperosmolarity resulted in diminished transport from the vascular to mesothelial side of the membrane, as compared to the control. With a stabilization of the transport to opposite direction, the resultant net transport approached zero. Analysis of the obtained results revealed more complicated nature of the mechanism of MTX transport across peritoneal membrane than that of a simple diffusion.