Insulin Resistance and Renal Sodium Handling Influence Arterial Stiffness in Hypertensive Patients with Prevailing Sodium Intake

Abstract

Abstract BACKGROUND Insulin resistance and renal tubular sodium handling influence arterial structure and function and play an essential role in salt-sensitive forms of hypertension. METHODS In a population with prevailing sodium consumption, we assessed the relationship between cardiovascular phenotypes (peripheral and central blood pressures, elastic properties of large arteries, the left ventricular structure) and sodium handling parameters (daily urinary sodium excretion, fractional urinary lithium excretion in proximal—FELi and distal tubules), as a function of insulin sensitivity—measured by homeostasis model assessment–insulin resistance (HOMA-IR), leptin-to-adiponectin (L/A) ratio, and homeostasis model assessment–adiponectin (HOMA-AD). RESULTS In patients with FELi below the median value (corresponding to the group with increased proximal sodium reabsorption) and higher insulin resistance as measured by HOMA-IR, pulse wave augmentation indexes were significantly higher—AIxP (99.4% vs. 86.2%; P = 0.007), AIxC1 (159.4% vs. 144.2%; P = 0.04), and AIxC2 (36.1% vs. 28.3%; P = 0.02), than in patients with lower insulin resistance. The same trend was observed in relation to L/A ratio—AIxP (98.7% vs. 87.1%; P = 0.005), AIxC1 (158.6% vs. 144.5%; P = 0.02), and AIxC2 (35.6% vs. 28.5%; P = 0.01) and HOMA-AD—AIxP (99.7% vs. 83.8%; P = 0.001), AIxC1 (160.5% vs. 140.3%; P = 0.007), and AIxC2 (36.6% vs. 26.3%; P = 0.003). Such relationships were not observed in patients with FELi above the median value. CONCLUSIONS In the hypertensive population with prevailing sodium intake, insulin resistance and increased sodium reabsorption in proximal tubules may affect arterial wall function.