Plasma tumor necrosis factor alpha levels and insulin sensitivity in hypertensive subjects

Recent studies have shown that tumor necrosis factor-alpha (TNF alpha), sec reted by macrophage, adipocyte and muscle cells, are associated with insuli n resistance syndrome i.e., hyperinsulinemia, hypertriglyceridemia and decr eased high density lipoprotein (HDL) cholesterol levels. However, it is unc lear whether plasma TNF alpha levels relate to insulin resistance syndrome in subjects with essential hypertension who are also characterized by an in sulin resistance state. We recruited 85 nondiabetic subjects (45 men and 40 women) with essential hypertension and 85 nondiabetic subjects who were ma tched for age, sex and body mass index (BMI) to determine their fasting pla sma glucose, insulin and lipoprotein concentrations, their glucose and insu lin responses to an oral glucose challenge, and their degrees of insulin re sistance. Fasting plasma leptin and TNF alpha levels were measured by radio immunoassay and chemiluminescent enzyme immunometric assay respectively. To tal body fat mass was assessed by the bioelectrical impedance method. The r esults showed that fasting plasma leptin levels were similar between hypert ensive and normotensive subjects (7.9+/-0.6 vs 7.4+/-0.7 ng/ml, p=0.190). F asting plasma TNF alpha concentrations were not different between subjects with hypertension and normotension (10.5+/-0.5 vs 9.8+/-0.4 pg/ml, p=0.360) . Fasting plasma TNF alpha concentrations were not different across three s ubgroups of the insulin resistance both in hypertensive patients (8.4+/-0.4 vs. 10.9+/-1.6 vs. 9.9+/-1.0 pg/ml, p=0.297) and normotensive subjects (9. 2+/-0.7 vs. 9.3+/-0.9 vs. 9.7+/-0.9 pg/ml, p=0.875). Fasting plasma TNF alp ha values showed significantly positive correlations with triglyceride conc entrations (p<0.03) but negative correlation with HDL cholesterol concentra tions (p<0.04) in normotensive but not in hypertensive individuals. These r elations persisted even after adjustment for BMI and total fat mass. In con clusion, our data indicated that circulating levels of TNF alpha did not di ffer between hypertensive subjects and normotensive controls. Plasma TNF al pha concentrations correlated positively with fasting plasma triglyceride l evels and negatively with HDL cholesterol concentrations in normotensive bu t not in hypertensive subjects. The influence of TNF alpha on carbohydrate and lipoprotein metabolism in hypertensive patients deserves further invest igations.