Dietary regulation of phosphatidic acid synthesis from dihydroxyacetone phosphate and fatty acid by rat liver microsomes

Abstract

Abstract Phosphatidic acid synthesis from dihydroxyacetone phosphate and 1‐ 14 C‐palmitate was studied in liver microsomes of rats maintained on a stock diet (5% fat), fasted for three days after being fed the stock diet, or given a high fat diet (15% fat) or a fat free diet for a week after being fed the stock diet. The amounts of phosphatidic acid synthesized per minute per milligram of microsomal protein in rats ingesting a stock diet or a fat free diet were at least twice the levels observed in rats either fasting or maintained on a high fat diet. Following fasting, realimentation with either a fat free or high fat diet returned the microsomal capacity for phosphatidic acid synthesis to approximately the same level, which was higher than that observed in rats maintained on a stock diet. Analogous results were observed when glyceraldehyde 3‐phosphate was used as the glyceride‐glycerol precursor, probably because microsomes convert glyceraldehyde 3‐phosphate to dihydroxy‐acetone phosphate. These studies demonstrate that phosphatidic acid synthesis from dihydroxyacetone phosphate by particulate enzymes is influenced by diet.