title: Diurnal rhythms of bile acid production in the rat.
abstract: 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.
mesh_terms: D000311:Adrenal Glands / Q000502:physiology; D000818:Animals; D001647:Bile Acids and Salts / Q000096:biosynthesis*; D002793:Cholic Acids / Q000096:biosynthesis; D002940:Circadian Rhythm; D003624:Darkness; D005215:Fasting; D005938:Glucocorticoids / Q000494:pharmacology; D008297:Male; D009799:Ocular Physiological Phenomena; D051381:Rats
chemical_list: D001647:Bile Acids and Salts; D002793:Cholic Acids; D005938:Glucocorticoids