Mechanism of oral absorbent AST-120 in lipid abnormalities in experimental uremic rats

We have reported that oral sorbent AST-120 (AST) is effective in delaying the induction of dialysis in patients with chronic renal failure (CRF) because of its effect on lipid metabolism. To clarify the precise mechanism of AST in lipid abnormalities in CRF, we examined the effect of AST on plasma lipid profile, total bile acids (TBA), and lipoprotein lipase (LPL) activity in experimental uremic rats.

Uremic rats were prepared using male Wistar rats by ligating 5/6 of the renal artery. Uremic rats were randomly divided into two groups as follows: a control group in which rats were maintained on the standard diet and an AST group in which rats were maintained on a diet containing 5 g of AST per 100 g of standard diet for 10 weeks. Plasma LPL activity was measured as free fatty acid (FFA) generation after intravenous administration of heparin.

Plasma creatinine at 1.5 +/- 0.1 mg/dl was lower in the AST group than the 1.9 +/- 0.5 mg/ml level in the control group. AST significantly decreased plasma total cholesterol from 192 +/- 29 to 142 +/- 25 mg/dl, triglycerides from 198 +/- 71 to 99 +/- 38 mg/dl, and TBA from 19.6 +/- 2.6 mumol/liter to 8.8 +/- 3.5 mumol/ml. Plasma LPL activity at 0.22 +/- 0.01 mumol FFA/min/hr was significantly higher in the AST group than 0.15 +/- 0.03 mumol FFA/min/hr in the control group.

These results suggest that AST may improve plasma lipid abnormalities by binding to bile acids in the intestinal lumen and preventing their reabsorption and inhibiting the reduction of LPL activity in experimental uremic rats.