Oscillatory behavior of control-systems of calcium homeostasis in chickens

✍ Scribed by Dr. S. Hurwitz; Barbara Miller; A. W. Norman

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 773 KB
• Volume: 56
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/jcb.240560218

✦ Synopsis

Computer simulation of calcium homeostasis in chicks predicted an oscillatory behavior of bone calcium flow and kidney 25-hydroxyvitamin D,-I-hydroxylase with a periodicity of 56 h and a 9 h phase difference between the two signals. In growing chickens subjected to a light: dark cycle of 22:2 h, and intravenously dosed with W a , the temporal changes in plasma 45Ca could be described by an exponential decline with superimposed diurnal oscillations. The activity of the renal 25-hydroxyvitamin D,-I-hydroxylase in chicks subjected to a 12:12 h light: dark cycle ALSO followed diurnal oscillations, with a nadir at the beginning of the light period and a peak 12 h later. The production of 1,25-dihydroxyvitamin D3 by primary cultures of chicken kidney cells oscillated with a periodicity of 5.6 h or shorter. It is suggested that despite the differences in phase and periodicity between the simulation predictions and actual results, the oscillations in both 1 -hydroxylase and bone calcium flow could be coupled through the hormonal systems involved in regulation of plasma calcium.