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Norepinephrine metabolism in humans. Kinetic analysis and model
O A Linares1, J A Jacquez, L A Zech
1Department of Internal Medicine, University of Michigan Medical School, Ann Arbor 48109.
This study used a two-compartment model to analyze norepinephrine (NE) distribution and metabolism in humans. Upright posture altered NE kinetics, increasing input rate and decreasing clearance.
Area of Science:
- Pharmacokinetics
- Human Physiology
Background:
- Norepinephrine (NE) kinetics exhibit heterogeneity in humans.
- Understanding NE distribution and metabolism is crucial for physiological studies.
Purpose of the Study:
- To precisely quantify NE kinetics using compartmental analysis.
- To investigate the impact of posture on NE distribution and metabolism.
Main Methods:
- Infusion of radiolabeled norepinephrine ([3H]NE) in healthy subjects.
- Measurement of plasma NE specific activity in supine and upright positions.
- Application of a two-compartment model to analyze [3H]NE disappearance curves.
Main Results:
- Plasma [3H]NE disappearance curves consistently fit a two-compartment model.
- Upright posture significantly increased NE input rate into the extravascular compartment.
- Upright posture decreased NE volume of distribution and metabolic clearance rate from the central compartment.
Conclusions:
- A two-compartment model accurately describes human NE kinetics.
- Posture significantly influences NE distribution and metabolic clearance.
- Findings provide a more precise understanding of NE handling in humans.
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