title: Intermittent versus continuous administration of 1,25-dihydroxyvitamin D3 in experimental renal hyperparathyroidism.
abstract: Conflicting results have been reported regarding the efficacy of intermittent versus continuous administration of 1,25(OH)2D3 in renal secondary hyperparathyroidism. To address this issue we examined sham-operated control rats and hyperparathyroid rats with subtotal (5/6) nephrectomy (Nx). The Nx animals (20 to 22 animals per group) were subjected to three treatment protocols: (i) solvent treatment (Nx-solvent); (ii) two i.p. injections of 35 pmol 1,25(OH)2D3 on days 0 and 4 (Nx-bolus); and (iii) continuous infusion of 70 pmol 1,25(OH)2D3 over six days via osmotic minipump (Nx-infusion). All measurements were performed six days after start of treatment. As compared to sham-operated controls, the pre-pro-PTH/beta-actin mRNA ratio was 2.04-fold higher in Nx-solvent. Both modes of administration of 1,25(OH)2D3 resulted in inhibition of PTH mRNA concentrations relative to Nx-solvent. The pre-pro-PTH/beta-actin mRNA ratio was, however, significantly lower (P < 0.05) in Nx-bolus than in Nx-infusion (Nx-bolus 1.26 higher than sham-operated controls; Nx-infusion 1.65 higher than sham-operated controls). Aminoterminal PTH (N-PTH) serum concentrations were higher in Nx-solvent (52 +/- 4 pg/ml) than in sham-operated controls (32 +/- 3 pg/ml, P < 0.01). N-PTH concentrations in Nx-bolus (38 +/- 4 pg/ml) were significantly lower than in Nx-solvent (P < 0.01) and in Nx-infusion (46 +/- 4 pg/ml, P < 0.05). Parathyroid gland weight (microgram/g body wt) was higher in Nx-solvent (1.30 +/- 0.08 pg/ml) than in sham-operated controls (0.79 +/- 0.04 pg/ml, P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Internal Medicine, University of Heidelberg, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Reichel
authors.forename: A
authors.initials: A
authors.lastname: Szabo
authors.forename: J
authors.initials: J
authors.lastname: Uhl
authors.forename: S
authors.initials: S
authors.lastname: Pesian
authors.forename: A
authors.initials: A
authors.lastname: Schmutz
authors.forename: H
authors.initials: H
authors.lastname: Schmidt-Gayk
authors.forename: E
authors.initials: E
authors.lastname: Ritz
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000008:administration & dosage* / Q000097:blood / Q000627:therapeutic use; D006961:Hyperparathyroidism / Q000097:blood / Q000188:drug therapy* / Q000209:etiology*; D007260:Infusion Pumps; D007274:Injections, Intraperitoneal; D007676:Kidney Failure, Chronic / Q000150:complications*; D008297:Male; D009392:Nephrectomy; D009994:Osmolar Concentration; D010280:Parathyroid Glands / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D002117:Calcitriol