[In vitro effects of 24R,25-dihydroxyvitamin D3 on alkaline phosphatase and gamma-glutamyltransferase in the kidney of hypophysectomized rats].
The effects of 24R,25-dihydroxyvitamin D3 (24,25-(OH)2D3 on alkaline phosphatase (PAL), gamma-glutamyltransferase (GGT) and acid phosphatase (PAC) activities were investigated on renal cortex slices of hypophysectomized rats. Indeed after hypophysectomy renal 24,25-(OH)2D3 production was increased and renal PAL and GGT activities were decreased. After 5h incubation with physiological concentrations (0.1-10 nM) of 24,25-(OH)2D3 significant increases of PAL and GGT activities were produced. The maximum stimulation obtained with 1 nM was +23% for PAL and +26% for GGT as compared to controls. PAC was not modified. The time course of these effects was studied from 45 min to 8 h. In the presence of 24,25-(OH)2D3 (1 nM), delayed (3h) stimulation of PAL and GGT appeared. It reached the maximal value after 6h, +37% for PAL and +30% for GGT and persisted again at 8h. Cycloheximide added to incubation medium with steroid inhibited the stimulating effect on PAL only. Actinomycin D suppressed the induction of both enzymes, indicating that the observed actions of 24,25-(OH)2D3 depend on protein synthesis whose responsible mechanisms were different. These protein synthesis inhibitors did not modified enzymatic activities. Physiological significance of these renal effects is to be clarified.
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Laboratoires de Physiologie, de Biochimie appliquée (CHU), de Pharmacie clinique, UFR des Sciences Médicales et de Pharmaceutiques, Angers, France.
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Giraul
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Thuillier
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D015650:24,25-Dihydroxyvitamin D 3 / Q000494:pharmacology*; D000135:Acid Phosphatase / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000378:metabolism*; D000818:Animals; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D005260:Female; D007016:Hypophysectomy; D007672:Kidney Cortex / Q000187:drug effects / Q000201:enzymology*; D007700:Kinetics; D051381:Rats; D011919:Rats, Inbred Strains; D005723:gamma-Glutamyltransferase / Q000378:metabolism*
D003609:Dactinomycin; D015650:24,25-Dihydroxyvitamin D 3; D003513:Cycloheximide; D005723:gamma-Glutamyltransferase; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase
Effets in vitro de la 24R,25-dihydroxyvitamine D3 sur la phosphatase alcaline et la gamma-glutamyltransferase du rein de rat hypophysectomisé.