The localization and properties of membrane adenosine triphosphatases in the guinea-pig placenta.
The distribution and properties of cytochemically demonstrable phosphatases in the near-term guinea-pig placenta were examined using a strontium capture technique for sodium- and potassium-dependent adenosine triphosphatase (Na+, K+-ATPase) and a lead capture technique for magnesium-dependent adenosine triphosphatase (Mg2+-ATPase). Localizations with the strontium technique in the presence of an alkaline phosphatase inhibitor were mainly on the syncytiotrophoblast plasma membranes; the reaction was potassium-dependent and ouabain-sensitive. Reaction product using the lead capture method was found on both trophoblast and endothelial cell plasma membranes and was independent of magnesium and insensitive to p-hydroxymercuribenzoate (POHMB), an inhibitor of membrane ATPases. However, a very large proportion of this reaction could be blocked by an alkaline phosphatase inhibitor. It is concluded that the strontium capture technique gave a reliable localization for Na+, K+-ATPase. However, the lead capture method mainly demonstrated alkaline phosphatase, and does not offer a useful approach to specific ATPase studies in this particular system.
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D005260:Female; D006168:Guinea Pigs; D006651:Histocytochemistry; D008274:Magnesium / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D010920:Placenta / Q000378:metabolism* / Q000648:ultrastructure; D011247:Pregnancy; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013773:Tetramisole / Q000494:pharmacology
D010042:Ouabain; D013773:Tetramisole; D000251:Adenosine Triphosphatases; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium