Histochemical localization of phosphatases in the pig placenta: II. Potassium-dependent and potassium-independent p-nitrophenyl phosphatases at high pH; relation to sodium-potassium-dependent adenosine triphosphatase.
Histochemical localization by Mg2+ capture methods of K+-dependent, ouabain-sensitive phosphatase activity in the pig placenta shows that strong Na+,K+-dependent adenosine triphosphatase (Na+,K+-ATPase) activity is restricted to the basal zone of the columnar epithelium covering the areolar chorionic villi. It is proposed that active Na+ absorption at this epithelium may be the source of the ouabain-sensitive, fetal-side-positive potential difference which can be measured across the placental membrane in vitro. The one-step procedure for Na+,K+-ATPase localization is unsatisfactory in this organ as any specific ATPase reaction is swamped by activity probably attributable to uteroferrin and other non-specific phosphatases.
D009597:4-Nitrophenylphosphatase / Q000032:analysis* / Q000378:metabolism; D000818:Animals; D003035:Cobalt; D005260:Female; D006651:Histocytochemistry / Q000379:methods; D006863:Hydrogen-Ion Concentration; D008274:Magnesium; D010744:Phosphoric Monoester Hydrolases / Q000032:analysis*; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis*; D013324:Strontium; D013552:Swine
D003035:Cobalt; D010744:Phosphoric Monoester Hydrolases; D009597:4-Nitrophenylphosphatase; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium; D013324:Strontium