Factors determining human chorion laeve permeability in vitro.
An increased mean diffusion permeability across human chorion laeve in vitro was measured for meperidine (D = 5.26 x 10(-6) cm.2 sec.-1) and diazepam (D = 4.51 X 10(-6) cm.2 sec.-1). These values corresponded to large chloroform-buffer partition coefficients (49 and 29) measured for these two compounds. Diffusion permeability values of 3.98 and 2.18 x 10-6 cm.2 sec.-1 measured for urea and glucose corresponded to their relative insolubility in lipid, as indicated by chloroform-buffer partition coefficients of 0.05 and 0.0004, respectively. An increase in placental permeability in vitro to the weak organic acid 5,5-dimethyl, 2,4-oxazalidinedione at lower pH's corresponded to an increase in the fat-soluble nonionized fraction of this compound. These data support the concept that this tissue is most permeable to compounds of relatively small molecular size and/or with a high level of lipid solubility. The large diffusion permeability values measured for meperidine and diazepam suggest that these compounds will diffuse rapidly between mother and fetus at a maximal rate limited only by uterine blood flow.
D002463:Cell Membrane Permeability; D002823:Chorion / Q000378:metabolism*; D003975:Diazepam / Q000378:metabolism; D004114:Dimethadione / Q000378:metabolism; D005321:Extraembryonic Membranes / Q000378:metabolism*; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008055:Lipids; D008431:Maternal-Fetal Exchange; D008614:Meperidine / Q000378:metabolism; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy; D012995:Solubility; D014508:Urea / Q000378:metabolism; D010130:p-Aminohippuric Acid / Q000378:metabolism
D008055:Lipids; D014508:Urea; D008614:Meperidine; D004114:Dimethadione; D005947:Glucose; D003975:Diazepam; D010130:p-Aminohippuric Acid