Abnormal intestinal regulation of calbindin-D9K and calmodulin by dietary calcium in genetic hypertension

C. M. Roullet, J. B. Roullet, P. Duchambon, M. Thomasset, B. Lacour, D. A. McCarron, T. Drueke

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14 Scopus citations

Abstract

Using isolated duodenal cells from spontaneously hypertensive rats (SHR) and their normotensive controls, Wistar-Kyoto rats (WKY), we previously showed that cellular calcium flux was decreased in SHR and that increasing dietary calcium (from 1 to 2%) eliminated strain differences in Ca2+ fluxes. The present study was carried out to investigate the role of calbindin-D9K and calmodulin in the flux difference and dietary calcium effects. Calbindin-D9K and calmodulin were separated by sodium dodecyl sulfate (SDS) gel electrophoresis in duodenal protein extracts of SHR and WKY (12-14 and 24-26 wk old) fed either a 1 or 2% calcium diet and measured by a ligand blotting (45Ca) technique. Young SHR had a significantly lower calbindin-D9K (P < 0.001) than did WKY on either diet. Calmodulin was significantly lower in young SHR than in WKY (P < 0.002). There was no strain difference in calmodulin in older rats fed the normal calcium diet. Calbindin-D9K was significantly decreased by the high-calcium diet in both strains at both ages. There was a significant correlation between duodenal calbindin-D9K and plasma levels of calcitriol (r = +0.80, P < 0.001) in WKY but not in SHR. Calmodulin was significantly decreased by dietary calcium in mature WKY (4.8 ± 0.2 vs. 3.7 ± 0.4 μg/mg cell protein, P < 0.03), demonstrating a potential regulation by dietary calcium of this protein. Finally, there was a significant correlation between calbindin-D9K and calmodulin (r = 0.59, P < 0.001) in WKY but not in SHR. In conclusion, the study points to abnormal regulation of both duodenal calbindin-D9K by calcitriol and duodenal calmodulin by dietary calcium in SHR. These findings probably explain previous observation of a different modulation of calcium fluxes by a high-calcium diet in SHR compared with WKY.

Original languageEnglish (US)
Pages (from-to)F474-F480
JournalAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Volume261
Issue number3 30-3
StatePublished - Jan 1 1991

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Keywords

  • Age
  • Calcitriol
  • Duodenum
  • Enterocytes
  • Ligand blotting
  • Spontaneously hypertensive rats

ASJC Scopus subject areas

  • Physiology

Cite this

Roullet, C. M., Roullet, J. B., Duchambon, P., Thomasset, M., Lacour, B., McCarron, D. A., & Drueke, T. (1991). Abnormal intestinal regulation of calbindin-D9K and calmodulin by dietary calcium in genetic hypertension. American Journal of Physiology - Renal Fluid and Electrolyte Physiology, 261(3 30-3), F474-F480.