Glomerular hemodynamics and arterial function in normal individuals

OBJECTIVE: To determine the relationship between arterial function (stiffness and wave reflection) and glomerular hemodynamics. METHODS: In 49 healthy normotensive individuals, glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured by urinary clearances of 99mTC-DTPA and 131I-hippuran, respectively. Filtration fraction was computed as GFR/ERPF. Arterial stiffness was estimated by carotid-femoral pulse wave velocity (PWV). Wave reflection was evaluated by carotid augmentation index (AIx), reflection magnitude and the round-trip travel time of the pressure wave. RESULTS: PWV and round-trip travel time were not independently correlated with any renal hemodynamic parameter or urinary albumin-creatinine ratio (UACR). AIx and reflection magnitude were directly correlated with filtration fraction (r = 0.35 and 0.37, respectively) and UACR (r = 0.43 and 0.53, respectively). When the population was divided into quartiles of reflection magnitude, filtration fraction and UACR progressively increased from the lowest to the highest quartile and after adjustment for age, mean arterial pressure, heart rate but also sex for UACR (P linear trend = 0.031 and 0.001, respectively). CONCLUSION: It is suggested that in normal individuals, the amplitude of wave reflection but not arterial stiffness is associated with signs evocative of increased glomerular pressure (filtration fraction and UACR), independently of systemic blood pressure.