Protein malnutrition and the function and fluidity of the intestinal microvillus membrane in growing rats.

The effect of protein malnutrition on the function, fluidity and composition of the intestinal microvillus membrane was studied in growing rats. Weanling male rats were fed diets containing 10% protein derived from either wheat gluten (experimental diet) or casein (control diet). Intestinal microvillus membranes were isolated after a 7-wk feeding period. The functionality of the membranes, as assessed by the level of activity of the four enzymes alkaline phosphatase, gamma-glutamyl transpeptidase, leucine aminopeptidase and maltase, showed no difference between the membranes derived from the experimental and the control animals. Similar Arrhenius plot patterns of alkaline phosphatase activity (13-50 degrees C) and of the fluorescence anisotropy parameter (8-40 degrees C) were observed for both types of membranes with respect to the transition temperatures and energies of activation. In addition, the similarity between the membranes derived from the experimental and the control animals was also manifested in the cholesterol and phospholipid content. The study demonstrates that despite the extreme nutritional stress exerted on the gluten-fed rats, the integrity and functionality of the intestinal microvillus membrane was adequately maintained.