Inhibitory Effects Of Ethaverine, A Homologue Of Papaverine, On Dopamine Content In Pc12 Cells

The inhibitory effects of ethaverine on dopamine content in PC12 cells a ere investigated. Ethaverine decreased dopamine content in a concentration-dependent manner in PC12 cells and showed 33.6% inhibition of dopamine content at a concentration of 1.0 muM for 24-48 h. The IC50 value of ethaverine was 1.4 muM. Dopamine content was lowered at 6 h and reached a minimal level at 12 h after exposure to ethaverine at 2.0 muM. The decreased dopamine level was maintained up to 48 h and then recovered to the control level at about 72 h. Tyrosine hydroxylase (TH) was inhibited at 6 h following treatment with ethaverine in PC12 cells and the activity was maintained at a reduced level up to 36 h (12-22% inhibition at 2.0 muM). These results indicate that ethaverine leads to a decrease in dopamine content by inhibition of TH activity.