Abstract :
Hypertension frequently occurs in the presence of the insulin resistance syndrome. Studies in animal models and in Caucasian and Mexican American populations suggest insulin resistance in hyperinsulinemia precede the development of hypertension. The mechanisms by which insulin resistance and hyperinsulinemia influence blood pressure are unknown, although insulin-induced increases in renal tubular sodium reabsorption, increases in sympathetic nerve activity, alter at vascular structure, and changes in intracellular calcium and magnesium are implicated. In Mexican American hypertensive probands (n=19) and their offspring (n=52), we found that insulin sensitivity, measured by euglycemic clamp, correlated inversely with body mass index (BMI), basal mean arterial pressure (MAP), salt sensitivity of blood pressure, and circulating triglycerides and correlated directly with high density lipoprotein (HDL) cholesterol. In addition, salt sensitivity of blood pressure correlated with carotid intimal wall thickness and left ventricular mass index. The relationships betweeninsulin sensitivity and salt sensitivity remain when adjusted for BMI and age. These data suggest that insulin resistance and hyperinsulinemia impact on renal handling of sodium and are associated with altered cardiovascular structure. Consideration should be given to potential aggravation of the insulin resistance syndrome in the treatment of hypertension.
