Biliary sterol, phospholipid and bile salt analyses. Bile salt, sterol and phospholipid contents from male Abcg8+/+ (n = 8), Abcg8+/- (n = 7), and Abcg8-/- (n = 5) mice were examined as described in Methods. Bile salt secretion following a 10 minute collection was lower in Abcg8+/- and Abcg8-/- mice compared to wild type (panel a), but these differences were not statistically significant. Biliary sterol and phospholipid were significantly reduced in the Abcg8-/- mice compared to the wild-type (panels b and c). *P < 0.05. The lower panel shows biliary bile salt, sterol and phospholipid secretion rates from female Abcg8+/+ (n = 5), Abcg8+/- (n = 4), and Abcg8-/- (n = 3) mice measured following 90-minute bile salt depletion followed by stepwise TUDC infusion as described in the text. Bars represent phase TUDC infusion rates. No differences were observed in the ability of the Abcg8-/- mice to secrete bile salts (panel d), but there is a marked inability of the knockout mice to secrete sterols (panel e) and a trend towards a reduced ability to secrete phospholipid (panel f) compared to wild type.