Enzymatic and transport studies in cholesterol-fed guinea pigs using intestinal brush border membrane vesicles.

The intestinal absorptive and digestive functions using the brush border membrane (BBM) vesicles were evaluated in guinea pigs receiving cholesterol-supplemented diet for 12 weeks. The Na+-gradient-dependent transport of D-glucose (p less than 0.001), L-alanine and L-phenylalanine (p less than 0.01) was decreased significantly the BBM of cholesterol-fed animals. The maximal velocity (Vmax) value of the sucrase and leucine aminopeptidase was decreased without any change in the affinity constant (Km) value, demonstrating that the enzyme contents were reduced in response to cholesterol-rich diet. However, both the Km and Vmax values of the alkaline phosphatase decreased markedly, suggesting that a new enzyme of increased substrate affinity had been formed due to intestinal adaptation of cholesterol load in diet. The present study demonstrated that cholesterol feeding caused a significant alteration in nutrients absorption, membrane enzymes and chemical composition of the small intestine.