Impact of Cocaine on Placental Function
In few studies the transport of cocaine and its effect on placental
function under ex vivo conditions was investigated. In a first study
using the ex vivo dually perfused human placentae with recirculation
of both maternal and fetal perfusates, 3
H-cocaine and 14C-inulin was
added to the maternal circulation [83]. Inulin was used as reference
marker for placental permeability. This study demonstrated that
cocaine is taken up relatively quickly by the maternal tissue side of
the placenta and transported to the fetal circulation. Steady state
levels were achieved within 20 minutes in the fetal circulation, which
were approximately 8% of the initial concentration of cocaine used in
the maternal circulation. The level of cocaine in the fetal circulation
remained higher than inulin. The permeability of inulin in the presence
of cocaine was significantly reduced. The permeability measured for
cocaine has indicated a similar permeability reduction as shown for
inulin. Although the uptake of 3
H-cocaine was much higher than
of inulin, the restriction of the transfer rate of cocaine compared to
inulin as expected by simple diffusion is apparently due to the receptor
binding site of cocaine in human placenta. In addition to the impact
of cocaine on the placental permeability, there was an additional effect
on placental hormone release function. After the addition of cocaine
to the maternal circulation the released rate of human chorionic
gonadotropin (HCG) into the maternal circulation was significantly
reduced.