Effects of Dietary Fats, Calcium, and Phosphorus on Rat Serum Alkaline Phosphatases

Abstract

I t has long been recognized that a fat enriched diet will result in an increased alkaline phosphatase activity of serum, lymph, and intestinal mucosa of rat (1, 2) and man ( 3 ) . Effect of the nature of fat, however, was not evaluated.I t was also shown that a low calcium diet leads to an increase in serum alkaline phosphatase activity of sheep (4) and poultry ( 5 ) . No attempts were made to differentiate the source of increased enzymes.Fishman et al. (6, 7) found that L-phenylalanine specifically inhibits intestinal alkaline phosphatase of human and rat. Using 5 mil4 L-phenylalanine, these investigators observed 78% inhibition of intestinal alkaline phosphatase of man and to a lesser extent that of rat. Based on these studies they concluded that the intestinal isoenzyme contributed 2 W 5 % of the total serum alkaline phosphatase in man. I n the rat most of the serum alkaline phosphatase originates from the striated border of the epithelial cells of intestine ( 8 ) , and thus may be involved in absorptive processes. The present study was undertaken to study the effect of the levels of dietary fat, calcium, and phosphorus and of the nature of fat on the activity of total and L-phenylalaninesensitive component of serum alkaline phosphatase of the rat.Materials and Methods. In all three experiments, weanling male rats of the Holtzman strain weighing 47-60 g were iar-notched and alloted to individual cages. Distilled water was provided ad libitum but only 7 g of diet per rat per day in the first two experiments and 8 g in the third experiment were allowed so that they consumed all the diet. The animals were maintained on the experimental * This study was supported by a grant from the Gebbie Foundation ; Xational Dairy Council, Grant No. 81; and by the funds provided through the State University of New York. diets for 1 week to adapt to the regimen and environment. They were then transferred to metabolism cages and tail cups were affixed to prevent coprophagy. Tail cups were emptied daily, the 7-day fecal collection for each rat was pooled, weighed, and kept frozen until analysis.I n the first experiment 210 rats were divided into 42 groups of 5 each. T h e composition of the basal diet is given in Table I. The fat content of the diets wits 0, 5, or 25% triolein, tripalmitin, or tristearin. \\'ith each level and type of fat three levels of calcium (0.08. 0.50, 2.06%) and three levels of phosphorus (0.15, 0.58, 1.67c/o), giving six calcium-to-phosphorus ratios (0.05, 0.57, 0.87, 1.23, 3.52, 13.75) were used. Calcium was added as calcium carbonate and phosphorus as potassium monobasic phosphate. All the additions were made a t the expense of cerelose.In the second experiment 20 rats were divided into four groups and fed diets containing 2 5 %, tristearin alone or supplemented with 5% triolein, 5% monoolein, or 2.5% monoolein plus 2.5% oleic acid.In the third experiment 30 rats were divided into six groups. Three of the six diets contained tripalmitin a t 10, 20, or 30c/(, levels. In the other 3 diets 5% triolein rep...