An independent relationship between plasma leptin and heart rate in untreated patients with essential hypertension.

OBJECTIVE: To test the hypothesis that hemodynamic measurements in patients with essential hypertension are related independently to plasma leptin levels. PATIENTS AND METHODS: We measured plasma leptin, insulin, office and ambulatory blood pressure and heart rate in 60 men with untreated mild hypertension. RESULTS: Plasma leptin correlated significantly with body mass index (r = 0.43, P = 0.001), 24 h heart rate (r = 0.35, P = 0.006) and 24 h diastolic blood pressure (r = 0.27, P = 0.04) but not with age (r = 0.03; P = 0.85) or 24 h systolic blood pressure (r = -0.08, P = 0.56). Plasma leptin levels adjusted for body mass index correlated significantly with 24 h heart rate (r = 0.36, P = 0.005) but not with 24 h diastolic blood pressure (r = 0.19, P = 0.15). We divided the patient population into tertiles of body mass index-adjusted plasma leptin levels. Age, plasma insulin, blood pressure, smoking status and physical activity habits were similar across the adjusted leptin tertiles. Patients from the third tertile of adjusted plasma leptin distribution (those with leptin levels higher than would be expected on the basis of body mass index) had significantly faster ambulatory heart rates than subjects from both the first and the second tertiles. The difference in heart rate across the three tertiles was most pronounced for the night-time values. CONCLUSIONS: In patients with essential hypertension, heart rate is faster in those patients with higher plasma leptin levels. This relationship is independent of age, body mass index, insulin levels, blood pressure level, smoking status and physical activity.