Stress modulation by electrolytes in salt-sensitive spontaneously hypertensive rats

Area of Science:

• Cardiovascular Physiology
• Nutritional Science
• Hypertension Research

Background:

• Dietary calcium (Ca) is a proposed nonpharmacologic treatment for hypertension, but its effects on blood pressure (BP) remain debated.
• Existing clinical studies lack a clear trend regarding the impact of nutritional Ca on BP.

Purpose of the Study:

• To conduct a meta-analysis of literature on the effect of dietary Ca on BP in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) controls.
• To investigate the modulation of stress sensitivity by dietary sodium (Na) and Ca in salt-sensitive SHR (SHR-S).

Main Methods:

• Meta-analysis of published data on the effects of dietary Ca on BP in SHR and WKY rats.
• Examination of stress sensitivity in SHR-S using body temperature changes during immobilization stress under varying dietary Na and Ca conditions.

Main Results:

• Dietary Ca supplementation significantly decreased BP in both SHR and WKY rats.
• Ca deprivation significantly increased BP in SHR.
• The hypotensive effect of dietary Ca was maximal in salt-sensitive SHR, particularly with a high Na/high Ca diet.
• High Ca diets prevented salt-sensitive hypertension in SHR-S, with high Na/high Ca being most potent.
• Ca intake attenuated stress sensitivity, while Na intake heightened it.

Conclusions:

• Dietary calcium plays a significant role in modulating blood pressure in hypertensive and normotensive rat models.
• Salt and stress sensitivity in hypertension appear to be related phenotypes modulated by dietary ions.
• High calcium intake, especially combined with high sodium, effectively lowers BP and reduces stress sensitivity in salt-sensitive hypertensive rats.