Diurnal rhythms in Ca transfer into bone, Ca release from bone, and bone resorbing activity in serum of rats

H. Shinoda, P. H. Stern*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

To characterize diurnal rhythms in calcium transfer in and out of bone, rats were adapted to a 12:12 h light-dark illumination program (with light from 0600 to 1800 h). For studies of deposition, rats were injected with 45CaCl2 at 0300, 0700, 1100, 1500, 1900 or 2300 h and killed with chloroform inhalation 60 min later, and radioactivity was determined in tibia and mandibular incisor. Peak deposition occurred at 2400 h, with a nadir at 1200 h. For studies of radionuclide release, rats were prelabeled with 45CaCl2 for 6 days and serum obtained from the tail at 4-h intervals. 45Ca and specific activity were maximal around 1200-1600 h and lowest late in the dark period. To determine the role of humoral factor(s), fetal rat limb bones were cultured in media prepared with sera from light-dark-adapted rats. Activity was maximal in serum collected at 0800 h and minimal at 1600 h. Heat inactivation at 100°C for 5 min eliminated the difference between the peak and nadir. The results suggest that a heat-sensitive humoral factor(s) regulates diurnal rhythms in calcium metabolism.

Original languageEnglish (US)
Pages (from-to)R235-R240
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume262
Issue number2 31-2
DOIs
StatePublished - 1992

Keywords

  • bone resorption
  • organ culture

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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