Selective effects of sodium and chloride depletion on salt appetite in rats.
Findings from hypertension research indicate that dietary sodium chloride (NaCl), Na+, and Cl- independently influence blood pressure, electrolyte metabolism, and hormone secretion. In this context, we examined the effects of NaCl, Na+, and Cl- depletion, respectively, on the development of saline preference (salt appetite) in rats. Male Wistar rats were given a normal diet (1% NaCl) for 15 days and tested for salt appetite using a two-bottle choice test, one bottle containing water and the other 0.3 M saline. The animals were then divided into three groups (n = 11/group): one group received low NaCl, another received a Na(+)-deficient, normal-Cl-diet (low Na+), and a third received a Cl(-)-deficient, normal-Na+ diet (low Cl-). Salt appetite was again tested after 19 days on these diets. Both NaCl and Na+ depletion stimulated saline intake (P less than 0.01), whereas salt appetite did not change in the low-Cl- group. Water intake was not influenced by the regimens. In addition, no alterations were noted for weight, systolic blood pressure, plasma Na+ concentration, or blood pH. Dietary Cl-depletion, however, significantly reduced plasma Cl- concentration (P less than 0.05), and reduced plasma potassium in relation to rats depleted in Na+ (P less than 0.05). Plasma renin activity and urinary aldosterone were elevated in low-NaCl and Na(+)-depleted rats relative to the Cl(-)-depleted group (P less than 0.05). These results suggest that salt appetite is increased by dietary Na+ deficiency but not by Cl- deficiency. Salt appetite may be controlled by central or peripheral systems specifically sensitive to Na+ or by hormonal changes characteristic of Na+ depletion, such as the activation of renin and aldosterone observed in the low-NaCl and low-Na+ groups.
Muntzel
M
M
Institute National de la Santé et de la Recherche Médicale, Department of Nephrology, Hôpital Necker, Paris, France.
Pouzet
B
B
Lacour
B
B
Hannedouche
T
T
Drüeke
T
T
D000450:Aldosterone / Q000652:urine; D000818:Animals; D001070:Appetitive Behavior; D002712:Chlorides / Q000494:pharmacology*; D002755:Choice Behavior; D003404:Creatinine / Q000097:blood; D004573:Electrolytes / Q000097:blood / Q000652:urine; D005518:Food Preferences; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012083:Renin / Q000097:blood; D012964:Sodium / Q000172:deficiency*; D012982:Sodium, Dietary; D014508:Urea / Q000097:blood
D002712:Chlorides; D004573:Electrolytes; D012982:Sodium, Dietary; D000450:Aldosterone; D014508:Urea; D012964:Sodium; D003404:Creatinine; D012083:Renin