In vitro C-20, 22 desmolase regulation of pregnenolone supply in first trimester human placenta

Homogenates of first trimester human placentae were incubated with [26-14C]chloresterol. Using reverse-isotope dilution analysis [14C]isocaproic acid was isolated and characterized. A progressive increase in [14C]isocaproic acid formation with increasing gestation suggestive of a regulatory mechanism at the C-20, 22 desmolase site in the supply of placental pregnenolone was noted.