Effects of chronic insulin treatment on blood pressure in rats

There is an evident epidemiological association between plasma insulin leve ls and blood pressure. The mechanism that relates insulin to blood pressure and the role of insulin in the pathogenesis of arterial hypertension have not been clearly defined. The present study was designed to examine the eff ects of chronic hyperinsulinism on blood pressure and to determine differen t related morphological variables. Wistar-Kyoto rats were subcutaneously in jected with insulin (25 UI/Kg of weight) daily during the eight weeks of th e experiment. Data were collected on systolic and diastolic arterial pressu res and heart rate by plethysmography and direct recording tin the last wee k), and on morphological variables. A statistically significant elevation o f systolic arterial pressure was produced after the sixth week of hyperinsu linaemia. At the end of the treatment, the systolic arterial pressure was 1 73.7 +/- 26.1 in the hyperinsulinaemic rats versus 153.09 +/- 21.7 in the c ontrol group. The values obtained by direct recording and by plethysmograph y did not differ. These results indicate that chronic hyperinsulinism produ ces a significant elevation in systolic blood pressure levels in the rats s tudied.