Nitric oxide does not participate in the metabolic effects of exogenous bradykinin in fructose-fed rats

The study was carried out to demonstrate the effects of bradykinin (BK) on hypertension, hyperinsulinemia, and hypertriglyceridemia in fructose-fed rats, and to determine whether these actions are mediated through nitric-oxide (NO) formation. Eighteen rats, rendered hypertensive, hyperinsulinemic, and hypertriglyceridemic by a fructose-enriched diet, were studied. BK (0.2 mg/day) was infused intravenously using osmotic pumps attached by a catheter to the jugular vein of 12 rats for 12 days. BK was administered either alone (n = 6) or with concomitant inhibition of NO synthase (n = 6). Six untreated rats served as control. Measurements of systolic blood pressure (indirect method) and levels of insulin and triglyceride in serum were taken every second day. BK infused chronically, induced a marked fall in all parameters as early as the second day of infusion: in blood pressure from 152+/-7 to 126+/-12 mmHg, in insulin from 8.7+/-2.9 to 4.6+/-5.4 pg/mL, and in triglyceride from 308+/-94 to 76+/-19 mg/dL. No such reduction was seen in untreated animals. When BK was administered concurrently with NO synthase inhibitor, blood pressure rose significantly, reaching very high values at the end of treatment. However, the reduction in insulin and triglyceride levels induced by BK was not affected. The capacity of BK to enhance reduction in hyperinsulinemia and hypertriglyceridemia in the fructose-fed rats is not mediated by NO formation. Whether this action of BK is related to a direct effect of this peptide remains to be determined.