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Ouabainlike factor in Milan hypertensive rats.
M Ferrandi1, E Minotti, S Salardi
1Prassis, Sigma-Tau Research Institute, Milan, Italy.
The American Journal of Physiology
|October 1, 1992
Summary
Ouabainlike factor (OLF) is present in higher amounts in hypertensive rats than normotensive controls. This finding supports the role of OLF in the development of genetic hypertension.
Area of Science:
- Endocrinology
- Cardiovascular Physiology
- Biochemistry
Background:
- Ouabainlike factor (OLF) is an endogenous compound with potential roles in blood pressure regulation.
- Previous studies suggested a link between OLF and hypertension, but direct evidence was lacking.
Purpose of the Study:
- To investigate and compare the levels of OLF in genetically hypertensive rats (MHS) and their normotensive controls (MNS).
- To characterize the biochemical properties of OLF and its interaction with Na-K-adenosinetriphosphatase (ATPase).
Main Methods:
- Extraction of OLF from rat hypothalamus and adrenal glands.
- Assay of OLF's inhibitory activity on ouabain-sensitive 86Rb uptake in human erythrocytes.
- Measurement of OLF's displacement of [3H]ouabain binding.
- Inhibition assays using purified dog kidney Na-K-ATPase and its isoforms.
Main Results:
- OLF was successfully extracted and characterized from both MHS and MNS rats, as well as bovine and rat tissues.
- OLF exhibited properties similar to ouabain, including inhibition of Na-K-ATPase and reduced activity with potassium.
- OLF showed distinct characteristics, with greater inhibition of low-affinity Na-K-ATPase isoforms and higher activity in adult rat enzymes.
- Significantly higher yields of OLF were obtained from MHS rats compared to MNS rats.
Conclusions:
- This study provides the first direct evidence of elevated OLF levels in genetically hypertensive rats.
- The findings strongly support the hypothesis that increased endogenous OLF contributes to the pathogenesis of MHS hypertension.