2A). Bilirubin is the product of erythrocyte and hemoglobin turnover [13]. Concentrations of bilirubin were much lower (at least 5-fold) in both SA and AB squirrels as compared to winter hibernators (Fig. 2B). However, there were no significant differences found for either cholesterol or free fatty acid concentrations as a function of state (Fig. 2C,D). It should be noted that there was marked individual

variation in the AB group squirrels for biliary free fatty acids with one squirrel demonstrating about a two fold higher concentration (not the squirrel with the large volume of bile). Figure 2 Bile constituents as a function of hibernation state. A) Bile acid concentrations in bile as a function of state. Values represent means ± SE from T (n = 3), IBA (n = 3), SA (n = 3), and AB squirrels (n = 4). AB was significantly lower than selleck kinase inhibitor all other states (ANOVA, p < 0.05). When different, letters above error bars denote significant differences. B) Bilirubin concentration in bile as a function of state. Values represent see more means ± SE from T (n = 3), IBA (n = 3), SA (n = 5), and AB squirrels (n = 4). There were no significant differences between T and IBA or between SA and AB.

All other values are significantly different (ANOVA, p < 0.05). C) Bile cholesterol concentration as a function of state. Values represent means ± SE from T (n = 3), IBA (n = 3), SA (n = 13), and AB squirrels (n = 4). There were no significant differences (ANOVA, p > 0.05). D) Free fatty acid concentrations in bile as a function of state. Values depicted are from each individual animal (means ± SE) to demonstrate individual variation and represent T (n = 3), IBA (n = 3), SA (n = 3), and AB squirrels (n = 4). There were no significant differences (ANOVA, p > 0.05). Lecithin or phosphatidylcholine was significantly lower in the AB group as compared to all other squirrels (Fig. 3A). A major function of lecithin is in the excretion of cholesterol during normal metabolism [13]. Osmolality was unchanged as a function of state (Fig. 3B). Torpor state had a significant effect on pH (Fig. 3C). Bile from winter hibernators (T and IBA) was significantly Ceramide glucosyltransferase more acidic than either SA

or AB bile. Indeed, hibernator bile had over 10 fold higher H+ concentration than AB bile (> 1.2 pH units). Bile protein concentration was significantly different as a result of state: hibernators (T and IBA) had approximately 5 fold higher protein levels than their AB counterparts (Fig. 3D). AB animals were more similar to SA squirrels. Figure 3 Bile constituents as a function of hibernation state. A) Bile lecithin/phosphatidylcholine concentration as a function of state. Values represent means ± SE from T (n = 3), IBA (n = 3), SA (n = 3), and AB squirrels (n = 4). AB was significantly lower than all other states (ANOVA, p < 0.05). When different, letters above error bars denote significant differences. B) Bile osmolality as a function of state.