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Measurement of plasma catecholamines in small samples from mice.
J B Lucot1, N Jackson, I Bernatova
1Department of Pharmacology, Wright State University School of Medicine, 3640 Colonel Glenn Hgwy, Dayton, OH 45435, USA. James.lucot@wright.edu
Journal of Pharmacological and Toxicological Methods
|August 30, 2005
Summary
This study presents a reliable method for measuring plasma catecholamines in mice using small blood samples. Findings reveal lower resting levels of norepinephrine and epinephrine than previously reported, highlighting the importance of euthanasia method selection.
Area of Science:
- Physiology
- Neuroscience
- Pharmacology
Background:
- Accurate measurement of plasma catecholamines is crucial for understanding sympathetic nervous system function.
- Previous methods required larger sample volumes, limiting studies in small animals like mice.
- Chronic catheterization offers a potential solution for repeated sampling in mice.
Purpose of the Study:
- To develop and validate a sensitive method for measuring plasma catecholamines (epinephrine and norepinephrine) in small blood samples from chronically catheterized mice.
- To establish baseline levels of plasma catecholamines in resting mice using the developed method.
- To compare the impact of different euthanasia methods on plasma catecholamine levels.
Main Methods:
- Systematic modification of standard alumina extraction procedures to optimize catecholamine recovery from 25-mul plasma samples.
- Utilized High-Performance Liquid Chromatography (HPLC) with electrochemical detection (EC), optimizing equipment per manufacturer guidelines.
- Compared plasma catecholamine levels in chronically catheterized mice with those obtained via CO2 plus decapitation and rapid decapitation.
Main Results:
- Achieved a limit of detection of 40 pg/ml for plasma noradrenaline and 20 pg/ml for plasma adrenaline.
- Established significantly lower resting plasma levels: 300 pg/ml for noradrenaline and 80 pg/ml for adrenaline.
- Observed differential increases in adrenaline and noradrenaline levels based on the euthanasia method employed, with increases comparable to immobilization stress.
Conclusions:
- The developed method is reliable, simple, and sensitive for measuring plasma catecholamines in mice.
- Resting plasma catecholamine levels in mice are lower than previously reported, suggesting method-dependent variations.
- The choice of euthanasia method significantly impacts plasma catecholamine measurements, necessitating careful consideration in studies of sympathetic function.