RESUMO
On day 20 of gestation, after ethanol feeding (27% ethanol calories, 25% protein), placental weights, DNA, RNA and water content were greater than in controls pair-fed an isocaloric diet without ethanol or those ad lib fed a pellet diet of similar composition. Rat litter size and fetal body, liver and brain weights were similar in all groups. In vivo fetal amino acid accumulation was significantly lower after alcohol exposure despite similar placental uptake. These results indicate that both placental hyperplasia and abnormal fetal amino acid uptake occur at a low alcohol dose when fetal body weight is unaffected.
Assuntos
Aminoácidos/metabolismo , Transtornos do Espectro Alcoólico Fetal/fisiopatologia , Placenta/fisiologia , Animais , Peso Corporal/efeitos dos fármacos , Encéfalo/crescimento & desenvolvimento , Etanol/farmacologia , Feminino , Transtornos do Espectro Alcoólico Fetal/metabolismo , Fígado/crescimento & desenvolvimento , Troca Materno-Fetal/efeitos dos fármacos , Tamanho do Órgão/efeitos dos fármacos , Placenta/efeitos dos fármacos , Gravidez , RatosRESUMO
The mechanisms for ascorbic acid transport were investigated in samples of human placenta obtained from normal term pregnancies. Results suggest that at very high ascorbic acid concentrations this vitamin may cross the placenta by simple diffusion. However, at lower ascorbic acid concentrations the predominant form of transport is carrier mediated and energy dependent. The energy used in the transport process can be derived from either glycolysis or oxidative phosphorylation. In addition, the transport system also requires the presence of sodium and of Na+-K+-dependent ATPase activity.
