PROLONGATION OF LIFE-SPAN IN HYPERTENSIVE RATS BY DIETARY INTERVENTIONS - EFFECTS OF GARLIC AND LINSEED OIL

The effects of long-term dietary application of garlic (dried powder, 0.5 % in weight of standard chow; G group) or linseed oil (2.5 %; L gr oup) as well as a combination of both interventions (L+G group) on the life span of hypertensive rats (SHR SP) was investigated. A further g roup fed with standard chow served as control (C). The dietary interve ntions were started at the age of three weeks. Besides regular measure ments of the systolic arterial blood pressure (oscillometrically at th e tail artery) as well as of heart rate and body weight, autopsy and h istological investigations were performed. Both diets, and particularl y their combination, prolonged life span significantly (mean values (d ays) C: 434.5 +/- 23.5; G: 453.2 +/- 16.2; L: 470.0 +/- 26.2; L+G: 494 .8 +/- 39.2). There was no significant interaction of the factors garl ic and linseed oil. Systolic blood pressure as measured during the com pensatory stage (data used until the 39th week of life) was significan tly lowered by both garlic (mean -5.8 mm Hg), linseed oil (mean -6.3 m m Hg), and their combination (mean -11.3 mm Hg). The animals died as a consequence of congestive left and right ventricular failure with ven tricular hypertrophy, dilatation, myocardial fibrosis and cellular inf iltration, left ventricular atrial thrombosis (in most cases), and ter minal pneumonia. On the other hand, arteriosclerotic plaques and signs of cerebral stroke could not be detected. Except for the degree of hy pertrophy, which was lower in the treated groups, no differences were obvious regarding the morphological findings at the time of death. The re was a significant positive correlation between mean blood pressure and the degree of left ventricular hypertrophy. Furthermore, a signifi cant negative correlation between mean blood pressure and ventricular hypertrophy on the one hand and survival on the other hand was obvious provided the total number of animals was considered, however, not wit hin the individual groups. The same applies to the relation between th e reduction of left ventricular hypertrophy and life span. The relativ ely slight hypotensive effect of both dietary interventions as well as the results of previous investigations speaks in favor of a substanti al influence of factors independent of blood pressure. In view of cont roversial results and interpretations in international literature, the mechanisms involved need further study.