The ontogeny of placental Na+-K+ ATPase in the mouse and its impairment by ethanol.
We have investigated the normal ontogeny of Na+-K+ ATPase in the mouse placenta and the possibility that impairment in placental transport capacity, as reflected in reductions in NA+-K+ ATPase activity, is associated with alcohol-related embryonic growth restriction. We have demonstrated that over the normal course of pregnancy there is a dramatic increase in placental NA+-K+ ATPase activity which occurs in concert with the embryofetal body growth spurt. Maternal ethanol administration during the early period of placental enzymogenesis (days 7-9) resulted in a significant reduction (up to 40%) of placental Na+-K+ ATPase activity on day 15. Both the severity and the frequency of the reduction were dose dependent. The effect was associated with significant reductions in embryonic body and brain weight but no change in body length or prenatal mortality. Incubation of term placental fragments for 2 h in increasing concentrations of ethanol resulted in a comparable reduction in enzyme activity. Our studies demonstrate that direct ethanol exposure produces a reduction of placental Na+-K+ ATPase activity, that exposure during the early stages of enzymogenesis results in persistent reductions in Na+-K+ ATPase activity in the mature placenta, and that this effect is associated with deficits of embryonic body and brain growth. A direct causal relationship has not been proven; however, it is conceivable that the correlation between reduced placental Na+-K+ ATPase activity and impaired embryofetal growth reflects a common causal pathway.
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D005314:Embryonic and Fetal Development / Q000187:drug effects; D000431:Ethanol / Q000494:pharmacology*; D005260:Female; D005865:Gestational Age; D051379:Mice; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D012016:Reference Values; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D000431:Ethanol; D000254:Sodium-Potassium-Exchanging ATPase