Prostaglandin protects against bile salt induced increases in proton permeation of duodenal brush border membrane.

A direct protective action of prostaglandin on luminal cell membranes was investigated by preincubating rabbit duodenal brush border membrane vesicles with prostaglandin E2 (PGE2) before incubation with bile salts. Membrane perturbation was assessed by measuring the net proton permeability (Pnet). Bile salts (deoxycholate, glycodeoxycholate, and taurodeoxycholate; 0.1-1.0 mmol/l) resulted in concentration dependent increases in Pnet: from (mean (SE] 5.42 (0.17) (n = 20) to 8.44 (0.24) x 10(-4) (n = 13) cm/s with 0.5 mmol/l deoxycholate. PGE2, 10(-8)-10(-6) mol/l, when added alone had no effect on Pnet: 5.41 (0.21) x 10(-4) (n = 14) cm/s with 10(-6) M PGE2. When duodenal brush border membranes were preincubated with PGE2, 10(-7)-10(-6) mol/l, however, the bile salt induced increase in Pnet was significantly reduced: 7.22 (0.18) x 10(-4) (n = 13) cm/s with 10(-7) mol/l PGE2 and 0.5 mmol/l deoxycholate. These findings indicate that PGE2 exerts a direct protective action on duodenal luminal membranes.