Calcium metabolic changes and calbindin-D in experimental hypertension.
OBJECTIVE
To examine renal and intestinal calbindin-D in relation to calcium metabolic changes in three different models of experimental hypertension.


METHODS
Spontaneously hypertensive rats (SHR), hypertension-prone Dahl salt-sensitive (Dahl-S) rats and the Goldblatt two-kidney, one clip rat model of renovascular hypertension were examined.


RESULTS
Both prehypertensive and hypertensive SHR had significantly lower concentrations of both renal calbindin-D28k and intestinal calbindin-D9k than Wistar control rats. This was accompanied by hypocalcaemia, hypomagnesaemia and increased plasma 1,25(OH)2 vitamin D levels. Induction of hypertension in Dahl-S rats reduced intestinal calbindin-D9k and increased plasma levels of 1,25(OH)2 vitamin D, while renal calbindin-D28k levels, plasma calcium levels and plasma magnesium levels were unchanged. Renovascular hypertension was associated with a significant increase in the intestinal calbindin-D9k, plasma 1,25(OH)2 vitamin D, parathyroid hormone and magnesium levels, while renal calbindin-D2k, plasma calcium and phosphorus levels were unaffected.


CONCLUSIONS
These three models of experimental hypertension have clearly demonstrated three separate patterns in the regulation of renal and intestinal calbindin-D, which relate to different alterations of factors involved in calcium and magnesium metabolism. In all three models hypertension was accompanied by a significant increase in plasma concentrations of 1,25(OH)2 vitamin D. Only rats with renovascular hypertension showed increased intestinal calbindin-D9k levels, whereas reduced concentrations were found in the SHR and in the hypertensive Dahl-S rats. This indicates the existence of a resistance at the cellular level to 1,25(OH)2 vitamin D affecting the expression of calbindin-D in both SHR and Dahl-S rats.
Hemmingsen
C
C
Department of Nephrology, Rigshospitalet, University of Copenhagen, Denmark.
Staun
M
M
Lewin
E
E
Egfjord
M
M
Olgaard
K
K
D000818:Animals; D064092:Calbindin 1; D064026:Calbindins; D002118:Calcium / Q000378:metabolism*; D020022:Genetic Predisposition to Disease; D006973:Hypertension / Q000378:metabolism*; D006978:Hypertension, Renovascular / Q000378:metabolism; D008297:Male; D009994:Osmolar Concentration; D051381:Rats; D011918:Rats, Inbred SHR; D011919:Rats, Inbred Strains; D017208:Rats, Wistar; D064030:S100 Calcium Binding Protein G / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology
C576500:Calb1 protein, rat; D064092:Calbindin 1; D064026:Calbindins; D064030:S100 Calcium Binding Protein G; C576508:S100g protein, rat; D012965:Sodium Chloride; D002118:Calcium