Rapid (10-Minute) Stimulation of Rat Duodenal Alkaline Phosphatase Activity by 1,25-Dihydroxyvitamin D 3
1988; Oxford University Press; Volume: 123; Issue: 4 Linguagem: Inglês
10.1210/endo-123-4-1778
ISSN1945-7170
AutoresLeïla Ben Nasr, J.-D. Monet, Philip Lucas, Lydie Comte, Patricia Duchambon, ANNE SOPHIE MARTIN,
Tópico(s)Endoplasmic Reticulum Stress and Disease
ResumoRecent reports have suggested that the action of calcitriol is much more rapid than previously thought. It is thus possible that some actions do not depend on de novo protein synthesis. A precise microdensitometric technique has been used to characterize the time course of the intestinal brush border alkaline phosphatase (AP) response of rat duodenal villi to the administration of calcitriol as AP activity has been shown to be dependent on the vitamin D status of the animal. The technique enables AP activity to be determined in situ without tissue disruption. After ip administration of 200 ng calcitriol to vitamin D-deficient male Wistar AF rats, a biphasic AP response was observed with an early peak within 1 h (0.068 ± 0.011 vs. 0.101 ± 0.003 integrated extinction (IE) min · μm3 × 103, P < 0.05) and a second at between 6 and 8 h (0.088 ± 0.005 vs. 0.172 ± 0.003 IE/min · μm3 × 103, P < 0.001). In a further experiment, the early response to calcitriol was reexamined with observations at 0,10, 30, 45, and 60 min after administration of either calcitriol or vehicle (n = 5 pairs per time point). AP activity was significantly increased in the calcitriol group compared with the vehicletreated group as early as 10 min after administration (0.132 ± 0.003 vs. 0.151 ± 0.005 IE/min · μm3 × 103, P < 0.02) and reached a peak 45 min after administration at which time AP activity was equal to that found in normal vitamin D-replete animals (0.193 ± 0.003 vs. 0.192 ± 0.002 IE/min · μm3 × 103, P > 0.5). The speed of this response indicates it to be unlikely to depend on de novo protein synthesis. (Endocrinology123: 1778–1782, 1988)
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