BLOOD-PRESSURE CHANGES INDUCED BY CHRONIC INSULIN-TREATMENT IN WISTARRATS

Hyperinsulinaemia may play a causal role in the development of hyperte nsion in obese hypertensives. However, experimental evidence supportin g this statement is inappropriate. The main purpose of this study was to evaluate the chronic effects of insulin administration on blood pre ssure, total-body glucose metabolism and urinary catecholamine excreti on. After 10 weeks of insulin injection blood pressure was substantial ly increased in insulin-treated animals compared to those treated with saline (125+/-2 vs 108+/-2 mm Hg, p<0.001). There were no differences in glycaemia, plasma triglyceride levels and free fatty acid levels b etween these two groups. Plasma level of corticosterone was increased in both insulin-treated and saline-treated rats as compared to untreat ed animals suggesting that the level of stress was similar in both inj ected groups. The urinary excretion of norepinephrine and dopamine was increased in the insulin-injected group by about 120 % and 310 %, res pectively. Our data clearly indicate that long-term insulin administra tion increased blood pressure but the underlying mechanisms remain to be elucidated.