Exogenous 25-hydroxycholecalciferol does not attenuate salt-induced hypertension.
We have reported that an inverse relationship exists between blood pressure and plasma concentration of 25-hydroxyvitamin D, the precursor of the hormonal form of vitamin D, for Dahl salt-sensitive rats fed a high salt diet. Plasma 25-hydroxyvitamin D concentrations decreased with time on the diet, as blood pressure increased. Experiments were conducted to determine whether the blood pressure increase of salt-sensitive rats fed a high salt diet could be attenuated by exogenous 25-hydroxycholecalciferol. Dahl salt-sensitive rats were fed a high salt diet and administered exogenous 25-hydroxycholecalciferol via subcutaneously implanted Alzet pumps. Exogenous 25-hydroxycholecalciferol (various doses from 28 to 80 microg/kg body weight-day) had no significant effect on the blood pressure of vitamin D-replete rats fed a high salt diet for 15 days. When exogenous 25-hydroxycholecalciferol (28 and 60 microg/day-kg body weight) was administered to vitamin D-depleted salt-sensitive rats, plasma 25-hydroxyvitamin D concentrations of the rats fed a low salt diet (26 +/- 2 and 59 +/- 6 nM) were proportional to the 25-hydroxycholecalciferol concentration in the pumps. Plasma 25-hydroxyvitamin D concentrations of the rats fed a high salt diet (18 +/- 1 and 23 +/- 3 nM) were not proportional to the 25-hydroxycholecalciferol concentration in the pumps, but were inversely proportional to the blood pressure of the rats. These data indicate no ameliorating effect of exogenous 25-hydroxycholecalciferol on salt-induced hypertension, but accelerated metabolism and/or clearance of 25-hydroxycholecalciferol in salt-induced hypertension.
Thierry-Palmer
M
M
Department of Biochemistry, Morehouse School of Medicine, Atlanta, Georgia 30310-1495, USA. thierrm@link.msm.edu
Tewolde
T K
TK
Wang
M
M
Carlyle
K S
KS
Forté
C
C
Bayorh
M A
MA
Emmett
N L
NL
Williams
E F
EF
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002112:Calcifediol / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D006973:Hypertension / Q000209:etiology* / Q000503:physiopathology / Q000517:prevention & control*; D015918:Infusion Pumps, Implantable; D008297:Male; D051381:Rats; D020303:Rats, Inbred Dahl; D012965:Sodium Chloride / Q000008:administration & dosage
D012965:Sodium Chloride; D002112:Calcifediol