ANTIHYPERTENSIVE EFFECTS OF VANADIUM COMPOUNDS IN HYPERINSULINEMIC, HYPERTENSIVE RATS

Although considerable evidence lends credence to the association betwe en insulin resistance, hyperinsulinemia and essential hypertension, th e precise nature of this relationship remains unexplained. In the pres ent investigation, we examined the proposition that these metabolic de fects contribute causally to the development of high blood pressure. I f these metabolic abnormalities were responsible for the development o f hypertension, then drug interventions that improve these defects sho uld also decrease high blood pressure. Since previous studies have dem onstrated that vanadium compounds enhance insulin action and lower pla sma insulin levels in nondiabetic rats, we examined the effects of the se compounds on insulin sensitivity, plasma insulin concentration and blood pressure in two hyperinsulinemic models of experimental hyperten sion. The animal models studied were the genetically predisposed spont aneously hypertensive rat and the fructose-hypertensive rat, where hyp ertension is induced in normotensive rats by feeding them a high fruct ose diet. Vanadium compounds caused marked and sustained decreases in plasma insulin concentration and blood pressure in both the animal mod els studied. Furthermore, the effect of the drugs on blood pressure wa s reversed by restoring plasma insulin levels in the drug-treated rats to those observed in their untreated counterparts. These data suggest that either hyperinsulinemia contributes to the development of hypert ension in both the spontaneously hypertensive and the fructose-hyperte nsive rats or that the underlying mechanism is closely related to the expression of both these disorders.