INSULINEMIA AND PANCREATIC ALPHA(2)-ADRENOCEPTORS IN SALT-SENSITIVE (SBH) AND SALT-RESISTANT (SBN) SABRA RATS - EFFECT OF HIGH-SALT DIET

Studies in humans have suggested that hyperinsulinemia might play an i mportant role in salt sensitivity and in the later development of high blood pressure. This possibility has been tested in this study on Sab ra rats, an animal model of salt-induced hypertension. Salt-sensitive (SBH) and salt-resistant (SBN) Sabra rats have been submitted to eithe r a normal (0.2% NaCI) or a high salt (8% NaCl) diet for 6 weeks. Comp arisons of blood pressure, basal glucose and insulin levels, and insul in response to glucose overload (1 g/kg) have been made. As pancreatic alpha(2)-adrenergic receptors are implicated in the control of insuli n release, their densities have been determined on plasma membranes by saturation studies with [H-3]-RX-821002 as the specific radioligand. Under normal diet, blood pressures were respectively 133 +/- 9 and 108 +/- 10 mm Hg (n = 6) in SBH and SBN. Basal glucose and insulin levels and insulin response to glucose overload were found to be significant ly higher in SBH than in SBN. In contrast, alpha(2)-adrenergic recepto r densities were lower (P <.001) in SBH when compared to SBN. High sal t diet increased (P <.01) blood pressure, decreased basal glucose (P < .01) and insulin (P <.001) levels only in SBH. However, when compared to SBN the insulin response to glucose overload was maintained higher in SBH. alpha(2)-Adrenergic receptor densities and difference between SBH and SBN did not differ from those found in normal diet. In conclus ion, the salt-induced high blood pressure of salt-sensitive Sabra rats is not associated with hyperinsulinemia and insulin resistance. Indee d, an improvement in the insulin sensitivity appears to be induced by either a high salt diet or high blood pressure. Am J Hypertens 1998;11 :790-795 (C) 1998 American Journal of Hypertension, Ltd.