P-glycoprotein (PgP) is the major drug efflux pump in human cerebral microvessels. PgP prevents pathogens, toxins and therapeutic drugs from entering the CNS. Understanding the molecular regulation of PgP activity will suggest novel mechanisms to improve CNS drug delivery. Previously, we found that during peripheral inflammatory pain (PIP) (3 h after λ carrageenan injection in the rat paw), PgP traffics to the cortical microvessel endothelial cell plasma membrane concomitant with increased PgP activity. In the current study, we measured the changes in composition of PgP-containing protein complexes after PIP in rat microvessel isolates. We found that a portion of the PgP is contained in a multi-protein complex that also contains the caveolar proteins CAV1, SDPR, PTRF and PRKCDBP. With PIP, total CAV1 bound to PgP was unchanged; however, phosphorylated CAV1 (Y14P-CAV1) in the complex increased. There were few PgP/CAV1 complexes relative to total PgP and CAV1 in the microvessels suggesting CAV1 bound to PgP is unlikely to affect total PgP activity. However, both PgP and CAV1 trafficked away from the nucleus in response to PIP. These data suggest that P-CAV1 bound to PgP potentially regulates PgP trafficking and contributes to the acute PgP activity increase after a PIP stimulus.
Keywords: Blood–brain barrier; caveolin1; p-glycoprotein; pain; protein trafficking.