BILE IS AN IMPORTANT ROUTE OF ELIMINATION OF INGESTED ALUMINUM BY CONSCIOUS MALE SPRAGUE-DAWLEY RATS

We assessed the importance of bile as an excretory route for ingested aluminum (Al). Bile ducts in 30 male Sprague-Dawley rats were cannulat ed to allow both bile collection and reinfusion of bile acids. Five da ys after surgery, rats (average weight = 191 +/- 4 g) were given a sin gle oral dose of aluminum (0, 0.2, 0.4, or 0.8 mmol) as aluminum lacta te in 1 mi of 16% citrate by gavage. Bile was collected 1-7 h after do sing from unanesthetized rats. Biliary aluminum secretion was highest during the first hour of bile collection. All rats dosed with aluminum secreted significantly greater amounts of aluminum in bile than contr ol rats. However, biliary aluminum secretion did not vary among animal s given the different aluminum doses suggesting that biliary secretion of aluminum was saturated at these doses. Rats dosed with 0.8 mmol Al retained significantly greater amounts of aluminum in soft tissues th an those given 0.2 or 0.4 mmol Al, This result suggests that physiolog ical mechanisms were unable to prevent tissue aluminum accumulation in the rats given the highest dose.