Abstract
From 5 to 20 weeks of age, stroke-prone spontaneously hypertensive rats (SHRSP) were fed a diet, containing dry Euglena cells (Euglena gracilis Z: at 30.4% in diet) as a protein source (Euglena diet) and its effects on the activity of angiotensin I-converting enzyme (ACE) in serum and vascular tissues and on the aortic elastin content were studied. The effects of captopril, an ACE inhibitor, were also studied for comparison. 1) The Euglena diet had no significant effect on blood pressure. In the SHRSP administered captopril from 5 weeks of age, blood pressure elevation was inhibited. 2) The serum ACE activity in SHRSP fed the Euglena diet showed no difference from that in the control group fed a commercial stock chow. In the SHRSP administered captopril, the serum ACE activity was enhanced. 3) The thoracic aorta ACE activity was lowered more (p<0.05) in both the Euglena-fed and captopril-treated groups than in the control group. The mesenteric artery ACE activ ties in both experimental groups were somewhat lower than that in the control group. 4) The ratio of aorta weight to body weight was significantly lower (p<0.05) in the Euglena-fed and captopril-treated groups than in the control group. Higher levels of aortic elastin were observed in the Euglena-fed and captopril-treated groups (p<0.05). These results suggest that suppression of hypertrophy and reduction in elasticity of the vascular wall in SHRSP fed a Euglena diet are due to an inhibitory effect on vascular tissue ACE activity.
