Coordinated secretion of alkaline phosphatase into serum and intestine in fat-fed rats.

ABSTRACT

BACKGROUND: Fat feeding increases the activity of intestinal alkaline phosphatase in the serum. The mechanism underlying this increase is unknown. Surfactant-like particles (SLP) secreted by enterocytes have been implicated in this phenomenon. OBJECTIVE: To study the effect of feeding fish oil and protein synthesis inhibitors on alkaline phosphatase activity in serum and in different intestinal fractions. METHODS: Male albino rats were fed 2 mL of fish oil and were injected cycloheximide or actinomycin D. Alkaline phosphatase activity was determined in the serum and intestinal fractions (SLP, mucosa, muscularis). RESULT: Feeding fish oil significantly elevated alkaline phosphatase activity in serum (p< 0.001) and intestinal mucosa (p< 0.01). Administration of cycloheximide or actinomycin D significantly reduced alkaline phosphatase activity in serum (p< 0.01) and in intestinal mucosa (p< 0.05). BCIP staining of brush border alkaline phosphatase activity in acrylamide gels yielded similar results. CONCLUSIONS: These findings suggest a co-ordination between alkaline phosphatase synthesis and its assembly into lipoprotein vesicles, such as SLP, secreted by enterocytes in response to fat feeding.