Modifications induced by plasma of gestational hypertensive women on the Na+/K+-ATPase obtained from human placenta.

Autor: Cester, N., Rabini, R.A., Tranquilli, A.L., Lucarelli, G., Salvolini, E., Staffolani, R., Amler, E., Zolese, G., Mazzanti, L.
Zdroj: Molecular & Cellular Biochemistry; May1997, Vol. 170 Issue 1/2, p125-129, 5p
Abstrakt: In order to investigate the molecular mechanisms of the inhibition of Na+/K+-ATPase in Gestational Hypertension (GH), we incubated Na+/K+-ATPase purified from human placenta of 6 healthy normotensive women with plasma from 6 GH women and 6 healthy controls. We determined the enzyme activity by the method of Esman, and the anthroyl-ouabain-binding capacity, dissociation constant (Kd) and average lifetime values (τ) by the static and dynamic fluorescence of anthroyl-ouabain. The lipid annulus of the enzyme was studied by static and dynamic fluorescence of 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5- hexatriene (TMA-DPH). The addition of total and protein-free GH plasma to normal Na+/K+-ATPase significantly inhibited the enzymatic activity even at the lowest concentration studied (1:100), as well as the ouabain-binding capacity, Kd and τ. GH plasma significantly decreased the fluorescence polarization and lifetime values of TMA-DPH. These observations indicate that the inhibition caused by GH plasma on Na+/K+-ATPase might be due to a reduction of the number of active molecules or a modification of the ouabain-binding site suggesting the existence of digitalis-like factor. A link between the modification of the lipid moiety of the enzyme and the Na+/K+-ATPase inhibition might be hypothesized. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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