Cardiac production of B-type natriuretic peptide is inversely related to the plasma level of free fatty acids in obese individuals - possible involvement of the insulin resistance -.

B-type natriuretic peptide (BNP) is produced by the heart and its plasma level is increased with the severity of left ventricular (LV) dysfunction/hypertrophy. The normal heart preferentially utilizes fatty acids as energy substrates. Plasma BNP levels are reported to be lower in obese individuals. We examined the relationship between BNP production and plasma free fatty acids (FFA), homeostasis model assessment of insulin resistance (HOMA-IR), and LV dysfunction/ hypertrophy. We examined the plasma BNP levels and FFA at the aortic root (AO) and coronary sinus (CS) as well as hemodynamic parameters in 62 patients (38 men and 24 women, 62.5±11.7 yrs) who underwent cardiac catheterization. Log BNP (AO) had a significant positive correlation with log BNP (CS-AO) (r=0.877, P<0.001). Log BNP(CS-AO) had a significant negative correlation with BMI (r=-0.558, P<0.001), waist circumference (WC) (r=-0.574, P<0.001), log FFA(AO) (r=-0.643, P<0.001), log triglyceride (r=-0.431, P<0.001), and log HOMA-IR (r=-0.463, P<0.001) and a significant positive correlation with left ventricular mass index (LVMI) (r=0.403, P=0.001). The multivariable regression analyses including log HOMA-IR, LVMI, and age as an independent variable revealed that HOMA-IR and LVMI were significant predictors of log BNP (CS-AO) or BNP production (P=0.001 and 0.004, respectively). We conclude that plasma BNP levels are determined primarily by cardiac production and that insulin resistance is a significant predictor of cardiac BNP production independent of LV hypertrophy in obese individuals.