Effect of prostaglandin F2 alpha on Na+-K+-ATPase activity in luteal membranes.
Slices of rat corpora lutea (CL) incubated with prostaglandin F2 alpha (PGF2 alpha) in Krebs-Hensenleit (K-H) Ringer solution showed a decrease in Na+-K+-ATPase activity after 60 min of incubation. However, PGF2 alpha in vitro did not alter Na+-K+-ATPase activity of isolated luteal membrane fractions. Following PGF2 alpha-induced in vivo luteal regression, reduction of Vmax and elevation of the activation energy above transition temperature of the lipid phase of the membrane occurred without changes in Km, optimum pH and transition temperature. These results suggest that  reduction of Na+-K+-ATPase activity after PGF2 alpha treatment may be due to reduction in the number of enzyme molecules or to masking of the active site of the enzyme without any change in enzyme characteristics. In addition, a change in membrane-bound enzyme activity may be an early step in PGF2 alpha-induced luteolysis.
D000818:Animals; D003338:Corpus Luteum / Q000187:drug effects / Q000201:enzymology*; D000242:Cyclic AMP / Q000032:analysis; D015237:Dinoprost; D005260:Female; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007700:Kinetics; D008055:Lipids / Q000032:analysis; D011247:Pregnancy; D011460:Prostaglandins F / Q000494:pharmacology*; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis*; D013696:Temperature
D008055:Lipids; D011460:Prostaglandins F; D015237:Dinoprost; D000242:Cyclic AMP; D000254:Sodium-Potassium-Exchanging ATPase