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Genetic basis of NaCl-sensitive hypertension
Journal of Cardiovascular Pharmacology
|January 1, 1988
Summary
Dietary salt sensitivity, a genetically inherited trait, exacerbates hypertension in rats by altering central sympathetic nervous system activity. Calcium intake counteracts these salt-induced effects, suggesting opposing regulatory roles.
Area of Science:
- Cardiovascular Physiology
- Neuroendocrinology
- Genetics
Background:
- Dietary salt (NaCl) and calcium (Ca2+) intake significantly influence blood pressure regulation.
- Individual sensitivity to dietary salt and calcium varies, suggesting an inherited basis.
- Hypertension development is influenced by genetic factors affecting salt and calcium metabolism.
Purpose of the Study:
- To investigate the mechanisms underlying salt sensitivity in hypertension.
- To explore the role of the sympathetic nervous system and central noradrenergic pathways in salt-induced hypertension.
- To determine the influence of dietary calcium on salt sensitivity and blood pressure regulation.
Main Methods:
- Utilized spontaneously hypertensive rats (SHR) with salt-sensitive (SHR-S) and salt-resistant (SHR-R) substrains, alongside Wistar-Kyoto (WKY) control rats.
- Administered high NaCl and/or Ca2+ diets to assess effects on blood pressure and sympathetic activity.
- Measured circulating noradrenaline levels and ganglionic blockade responses.
- Assessed noradrenaline storage and release in the anterior hypothalamus.
Main Results:
- High NaCl diets exacerbated hypertension in SHR-S but not SHR-R or WKY rats.
- NaCl loading increased peripheral sympathetic activity and neurogenic vascular tone in SHR-S.
- Dietary NaCl reduced noradrenaline in the anterior hypothalamus of SHR-S, suggesting impaired central sympathetic inhibition.
- Dietary Ca2+ supplementation prevented or reversed NaCl-induced hypertension and sympathetic changes in SHR-S.
Conclusions:
- Salt sensitivity of blood pressure is genetically determined and linked to altered central noradrenergic activity.
- Reduced noradrenergic depressor function in the anterior hypothalamus may contribute to NaCl-induced hypertension.
- Dietary calcium exerts opposing effects to sodium, potentially through shared regulatory pathways.
- The genetic basis for salt/calcium sensitivity likely involves cellular cation transport mechanisms.