Effects of different bile salts upon the composition and morphology of a liver plasma membrane preparation. Deoxycholate is more membrane damaging than cholate and its conjugates

Abstract

1. Rat liver plasma membrane preparations were incubated with various bile salts at 0 or 37 degrees C. the bile salts caused the removal of various amounts of proteins, membrane enzymes and phospholipids; the extent and nature of these losses, and the morphological changes which accompanied them, varied with the detergent used. 2. Cholate, taurocholate and glycocholate removed appreciable amounts of protein from the saline-washed membranes, and considerable amounts of both phospholipids and the membrane enzymes, 5-nucleotidase, alkaline phosphatase, alkaline phosphodiesterase 1 and L-leucyl-beta-naphtylamidase. These losses were greater at 37 that at 0 degrees C. The material remaining contained membrane-like profiles, many of vesicular form, even when the preparation was almost completely devoid of phospholipids. 3. Deoxycholate, both at 0 and 37 degrees C, removed more protein, membrane enzymes and phospholipids than did cholate and its conjugates. The material remaining was mainly granular and unorganised and the only remaining features were structures resembling the nexus, and occasional desmosomes. 4. Deoxycholate, a dihydroxy bile salt, therefore appears to cause greater perturbation of membrane structure than the trihydroxy bile salt, cholate, and its conjugates. The results may have implications for the effects of bile salts upon the membranes of liver cells during bile salt secretion and the production of bile.