Change in $Na^+-K^+$-ATPase Activity in Regressive Corpus Luteal Membrane

황체퇴화시 황체막 $Na^+-K^+$-ATPase 활성도의 변화

Slices of rat corpora lutea(CL) incubated with. prostaglandin $F_{{2{\alpha}}}(PGF_{2{\alpha}})$ in Krebs-Hensenleit (K-H) Ringer solution showed a decrease in $Na^+-K^+$-ATPase activity after 60 min of incubation. However, $PGF_{2{\alpha}}$ in vitro did not alter $Na^+-K^+$-ATPase activity of isolated luteal membrane fractions. Following $PGF_{2{\alpha}}$ induced in vivo luteal regression, reduction of Vmax an elevation of the activation energy above transition temperature of the lipid phase of the membrane occurred without changes of Km, optimum pH and transition temperature. These results suggest that reduction of $Na^+-K^+$-ATPase activity after $PGF_{2{\alpha}}$ treatment may be due to the reduction of 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 $PGF_{2{\alpha}}$ induced luleolysis.