Circadian rhythm of plasma sodium is disrupted in spontaneously hypertensive rats fed a high-NaCl diet.
High-NaCl diets elevate arterial pressure in NaCl-sensitive individuals, and increases in plasma sodium may trigger this effect. The present study tests the hypotheses that 1) plasma sodium displays a circadian rhythm in rats, 2) the plasma sodium rhythm is disturbed in spontaneously hypertensive rats (SHR), and 3) excess dietary NaCl elevates plasma sodium concentration in SHR. The results demonstrate that plasma sodium has a circadian rhythm that is inversely related to the circadian rhythm of arterial pressure. Although the plasma sodium rhythms of SHR and control rats are nearly identical, the plasma sodium concentrations are significantly higher in SHR throughout the 24-h cycle. Maintenance on a high-NaCl diet increases plasma sodium concentration similarly in both SHR and control rats, but it blunts the plasma sodium rhythm only in SHR. These results demonstrate that in rats, plasma sodium has a circadian rhythm and that high-NaCl diets increase plasma sodium concentration.
Fang
Z
Z
Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019, USA.
Carlson
S H
SH
Peng
N
N
Wyss
J M
JM
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D004032:Diet; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017673:Sodium Chloride, Dietary / Q000097:blood* / Q000493:pharmacokinetics*; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*
D017673:Sodium Chloride, Dietary