Stress modulation by electrolytes in salt-sensitive spontaneously hypertensive rats.
Dietary calcium (Ca) has been proposed for the nonpharmacologic treatment of hypertension. However, its effect on blood pressure (BP) is debatable, and clinical intervention studies have not yet established a clear trend. The authors studied literature results on the effect of nutritional Ca on BP in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) controls, using the meta-analysis technique. Analysis of the data on inbred animals showed a clear effect of dietary Ca on BP: Ca supplementation produced a significant decrease in SHR and WKY rats, whereas Ca deprivation induced a significant increase in SHR. Furthermore, the hypotensive action of dietary Ca was maximal in salt-sensitive SHR (SHR-S), especially when given a high sodium (Na)/high Ca diet. Because the SHR-S may be more sensitive to stress than the salt-resistant SHR, the possible modulation of stress sensitivity by dietary Na and Ca in SHR-S was examined. High Ca regimens prevented salt-sensitive hypertension in SHR-S, with the high Na/high Ca diet being most potent in lowering BP. This BP reduction by Ca was paralleled by an attenuation of stress sensitivity, as measured by increased body temperature during immobilization stress. Therefore, stress sensitivity was heightened by dietary Na and diminished by dietary Ca (p < 0.05). It was concluded that salt and stress sensitivity in hypertension may be related phenotypes that are both modulated in parallel by dietary ions.
Dumas
P
P
Laboratoire de Pathophysiologie Moléculaire, Université de Montréal, Montréal, Québec, Canada.
Tremblay
J
J
Hamet
P
P
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001833:Body Temperature Regulation; D002136:Calcium, Dietary / Q000494:pharmacology*; D006973:Hypertension / Q000503:physiopathology*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012965:Sodium Chloride / Q000494:pharmacology; D012982:Sodium, Dietary / Q000494:pharmacology*; D013312:Stress, Physiological / Q000503:physiopathology*
D002136:Calcium, Dietary; D012982:Sodium, Dietary; D012965:Sodium Chloride