title: Changes in biliary lipid secretion during normal development and diurnal cycling in the rat.
abstract: Biliary lipid secretion in conjunction with hepatic cholesterol synthesis was determined in normal male rats at 4, 5, 7, and 9 weeks of age, during a period of linear growth and a near fourfold increase in liver size. Studies were performed both at periods of low (mid-light cycle) and high (mid-dark cycle) hepatic cholesterol synthesis. Biliary bile salt, phospholipid, and cholesterol secretion (per g of liver) markedly decreased with an increase in liver size. Whereas the secretion of bile salts and phospholipid was not significantly different in mid-dark and mid-light periods for animals of the same age, cholesterol secretion was greater in the mid-dark than in the mid-light period at 5, 7, and 9 weeks of age. Relationships between biliary cholesterol secretion and bile salt and phospholipid secretion differed at mid-dark and mid-light periods, as follows: cholesterol secretion was not significantly related to bile salt secretion at mid-dark (r = 0.49, P > 0.05) but was related at mid-light (r = 0.73, P = 0.003); and although cholesterol secretion was significantly related to phospholipid secretion at mid-dark, this relationship was not nearly as strong as at mid-light (P < 0.005, comparing r = 0.95 at mid-light with r = 0.53 at mid-dark). In contrast, at mid-dark, biliary cholesterol secretion was strongly related to hepatic cholesterol synthesis (r = 0.84, P < 0.0001) whereas at mid-light the two were not significantly related (r = 0.13, P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Division of Lipid Metabolism, Boston VA Medical Center, MA 02130.
authors.forename: S J
authors.initials: SJ
authors.lastname: Robins
authors.forename: J M
authors.initials: JM
authors.lastname: Fasulo
authors.forename: P D
authors.initials: PD
authors.lastname: Lessard
authors.forename: G M
authors.initials: GM
authors.lastname: Patton
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D001646:Bile / Q000378:metabolism*; D001647:Bile Acids and Salts / Q000378:metabolism; D002784:Cholesterol / Q000096:biosynthesis / Q000378:metabolism*; D002940:Circadian Rhythm; D050356:Lipid Metabolism; D008099:Liver / Q000254:growth & development* / Q000378:metabolism; D008297:Male; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D001647:Bile Acids and Salts; D010743:Phospholipids; D002784:Cholesterol