Serum aminopeptidase a activity of mice is related to dietary fat saturation

A high intake of monounsaturated fat has been proposed to be a dietary fact or that can decrease the incidence of cardiovascular disease and hypertensi on. In addition, increasing dietary fat saturation has been shown to increa se plasma total cholesterol and elevate systolic and diastolic blood pressu res. We demonstrated previously that cholesterol selectively increases in v itro aminopeptidase A activity, which is related to angiotensin metabolism. In this study, we investigated the effect of different degrees of dietary fatty acid saturation on serum aminopeptidase activities in vivo. Serum tot al cholesterol concentrations were also measured. Five groups of male Balb/ C mice were fed for 10 wk diets containing 2.4 g/100 g of sunflower oil, fi sh oil, olive oil, lard or coconut oil. We measured alanyl-, arginyl-, cyst inyl-, pyroglutamyl-, aspartyl- and glutamyl- specific aminopeptidase activ ities using arylamides as substrates. Serum total cholesterol levels were h igher in mice fed diets containing saturated oils (lard and coconut) than i n those consuming sunflower oil, which is unsaturated. Two of the serum ami nopeptidase A activities (aspartyl and glutamyl aminopeptidase) increased p rogressively with the degree of saturation of the dietary fatty acids; acti vities were significantly greater in mice fed coconut oil than in those fed sunflower or fish oil. Therefore, the substrates hydrolyzed by this activi ty as well as their functions may be similarly affected. These results may have some implication for the treatment of cardiovascular disease.