The effects of delta-9-tetrahydrocannabinol on actin microfilaments.

Fluorescence staining with rhodamine phalloidin specific for F-actin was employed to examine the effects of delta-9-tetrahydrocannabinol (THC) on the distribution of microfilaments in kangaroo rat epithelial cells (PtK2) and rabbit aortic endothelial cells (RAE). PtK2 cells were more sensitive to THC treatment than RAE cells. Exposure of PtK2 cells to 10 microM THC for 2 h disrupted the microfilament network. After treatment with 20 microM THC for 2 h there was a loss of cell-to-cell contact between PtK2 cells, and at 30 microM THC, the cells started to detach from the substratum. In contrast, microfilament disorganization but not cell detachment was observed in RAE cells at THC concentrations of 80 and 100 microM. The possible mechanisms which may account for the changes in the microfilament system are discussed.