AJP - Regulatory, Integrative and Comparative Physiology, Vol 236, Issue 3 175-R179, Copyright © 1979 by American Physiological Society
Diurnal rhythms of bile acid production in the rat
W. C. Duane, M. L. Gilberstadt and D. M. Wiegand
Diurnal rhythms of bile acid synthesis were studied in Sprague-Dawley rats
maintained in 12 h of illumination and 12 h of darkness each day.
Synthesis, measured as output from a chronic bile fistula, underwent a
consistent diurnal change with an amplitude of about 20% around mean daily
synthesis and a peak in the dark period. The peak in cholate synthesis
preceded the peak in chenodeoxycholate synthesis which preceded the peak in
alpha-muricholate synthesis which preceded the peak in beta-muricholate
synthesis. Fasting, intravenous infusion of dexamethasone (100 microgram/kg
. h), adrenalectomy, and ocular enucleation all failed to abolish the
diurnal rhythm in synthesis. In one rat studied 30 days after ocular
enucleation the diurnal rhythm in synthesis persisted; however, relative to
4 days after enucleation the phase of the rhythm shifted about 90 degrees
suggesting that light deprivation caused the rhythm to become free-running
with a period slightly different from 24 h.
