Altered effect of 3% dietary cholestyramine on plasma lipids and biliary bile acid output in the pregnant rat.

The effects of a diet containing 3% (w/w) cholestyramine on plasma total, free, and high-density lipoprotein cholesterol and triglycerides and on bile flow and composition were compared between pregnant rats fed the resin from before mating until the twentieth day of gestation and virgin rats fed the resin for an equivalent length of time. Pregnant and virgin rats consuming a similar diet but not receiving cholestyramine were also studied. In the nonpregnant rat the usual response to cholestyramine was observed as a significantly elevated plasma high-density lipoprotein cholesterol level and biliary bile acid secretion. Plasma cholesterol levels and bile composition were not altered by cholestyramine in the pregnant rat. The inability of resin therapy to change plasma high-density lipoprotein cholesterol and bile composition during pregnancy is likely to be causally related to a reduced efficacy of cholestyramine treatment when administered during gestation.