• G W Lambert, G Eisenhofer, and M D Esler.
• Human Autonomic Function Laboratory, Baker Medical Research Institute, Prahran, Vic, Australia.
• Psychoneuroendocrinology. 1994 Jan 1; 19 (1): 33-41.

AbstractUsing percutaneously placed arterial and venous catheters, we examined the influence of aging on the plasma concentration, whole body production rate, and renal clearance of homovanillic acid (HVA) in 60 healthy adult volunteers. The arterio-renal fractional extraction of HVA combined with the renal plasma flow (Fick Principle) were used to estimate the whole body HVA production rate and the renal plasma HVA clearance. The arterial HVA plasma concentration, whole body rate of HVA production, and HVA plasma clearance were determined to be 54 +/- 3 nmol/l, 27 +/- 2 nmol/min and 502 +/- 32 ml/min, respectively. The resting arterial HVA plasma concentration was positively correlated with aging, with the increased HVA concentrations in the older subjects being due to a diminished renal HVA plasma clearance. The diminished clearance of HVA occurred in response to a decreased renal plasma flow; the fractional extraction of HVA across the kidney remained unchanged with aging. This study emphasises the need for using age-matched control groups in neurochemical and neuropsychiatric studies, and demonstrates that increases in the arterial level of HVA do not necessarily reflect an increased rate of HVA production but may arise due to a diminished excretion rate of HVA from the body.

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