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Osmotically inactive skin Na+ storage in rats
Jens Titze1, Rainer Lang, Christoph Ilies
1Department of Nephrology, Friedrich-Alexander University Erlangen-Nuremberg, Loschgestrasse 8, D-91054 Erlangen, Germany. jus.titze@t-online.de
American Journal of Physiology. Renal Physiology
|July 31, 2003
Summary
Ovariectomy (OVX) in rats reduces the skin's capacity to store excess sodium (Na+), a key factor in salt-sensitive hypertension. This impaired storage may increase susceptibility to fluid retention, even with lower overall Na+ levels.
Area of Science:
- Physiology
- Endocrinology
- Hypertension Research
Background:
- Women exhibit resistance to salt-induced hypertension, but this protection diminishes post-menopause.
- Osmotically inactive sodium (Na+) storage in tissues is a proposed mechanism contributing to salt-sensitive hypertension.
- Menopause affects connective tissues, including skin, which may play a role in Na+ storage.
Purpose of the Study:
- To investigate if ovariectomy (OVX) reduces the body's capacity for osmotically inactive Na+ storage, particularly in the skin.
- To determine the impact of OVX on Na+ accumulation in skin under high-salt conditions.
Main Methods:
- Male, fertile female, and OVX female Sprague-Dawley rats were fed low (0.1%) or high (8%) NaCl diets for 4-8 weeks.
- Measurements included urinary Na+ and K+ excretion, body and skin water content, and total body and skin Na+ content relative to dry weight.
- Skin Na+ accumulation was assessed after high-salt diet exposure.
Main Results:
- Ovariectomy (OVX) reduced total body Na+ content in rats on both low and high-salt diets compared to fertile females.
- OVX significantly decreased Na+ content in the skin.
- While high-salt diets increased skin Na+ in all rats, OVX rats showed no osmotically inactive Na+ accumulation in the skin.
Conclusions:
- The skin acts as a reservoir for osmotically inactive Na+, accumulating Na+ during excessive dietary intake.
- OVX results in a reduced capacity for osmotically inactive Na+ storage in rats.
- This reduction in Na+ storage capacity due to OVX may predispose rats to volume expansion and hypertension.