In vitro inhibitory effect of cytochalasins on intestinal phenylalanine absorption in the mouse

Abstract

Inhibition of phenylalanine absorption by several cytochalasins was studied in the everted sacs of mouse jejunum in vitro. Five cytochalasins (A, B, C, D, and E) at a concentration of 10.0 μg/ml highly inhibited Na+-dependent phenylalanine absorption by 13.1 to 47.1%. Cytochalasin E appeared to be a most potent congener among other cytochalasins and it caused an inhibition of phenylalanine absorption by 32.6% at low concentration of 2.5 μg/ml. In the kinetic study, cytochalasin E induced an alteration of both K(m) (1.4 x 10-3to 2.3 x 10-3M) and V(max) (59.8 to 14.6 μmoles/g wet wt/60 min) values. It is suggested therefore that cytochalasin E may probably inhibit the absorption of actively transported amino acid in part by interfering with the binding sites of carriers on microvillar membrane.