Does increased leptin contribute to obesity hypertension?

Although plasma leptin concentration is markedly increased in hypertensive obese humans, the role of leptin in cardiovascular regulation is unclear. The aim of the present study was to determine if chronic elevation of plasma leptin, to levels that mimic those in obesity, alter renal function and increase blood pressure in normal Sprague-Dawley (SD) rats. Male SD rats (n=5) were implanted with arterial and venous catheters, and mean arterial pressure (MAP) and heart rate (HR) were monitored continuously, 24 hr/day. After 6 days of control measurements, a 5-day infusion of leptin (100 ng/kg/min, iv.) was started. Daily sodium intake was maintained constant at 2.8 mEq/day. Leptin infusion for 5 days did not significantly alter any variables that were measured. MAP HR Food UV U_NaV GFR (mmHg) (beats/min) (g/day) (ml/day) (mEq/day) (ml/min) Control 94±2 349±11 16±1 31±7 2.6±0.2 2.7±0.1 Leptin 95±2 34&11 16±1 32±6 2.5±0.2 2.8±0.1 [UV: urinary volume; U_NaV: urinary sodium excretion; GFR: glomerular filtration rate] These observations suggest that chronic elevation of plasma leptin, to values observed in obesity, have minimal effects on cardiovascular and renal function.