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Quantifying the L-arginine paradox in vivo
Nina Vukosavljevic1, Dov Jaron, Kenneth A Barbee
1School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA 19104, USA.
Microvascular Research
|December 1, 2005
Summary
Increased L-arginine availability significantly boosts nitric oxide (NO) production in the rat microcirculation, enhancing tissue perfusion. This study provides direct in vivo evidence supporting the L-arginine paradox.
Area of Science:
- Physiology
- Microcirculation Research
- Biochemistry
Background:
- Nitric oxide (NO) plays a crucial role in regulating microvascular function.
- The L-arginine paradox describes the complex relationship between L-arginine availability and NO production.
Purpose of the Study:
- To quantify the effects of increased L-arginine availability on NO and oxygen levels in the rat microcirculation.
- To investigate the impact of enhanced L-arginine on tissue perfusion in vivo.
Main Methods:
- Utilized NO and PO(2) microelectrodes to measure perivascular changes.
- Employed laser Doppler flowmetry (LDF) for simultaneous tissue perfusion measurements.
- Studied an exteriorized rat mesentery and small intestine microcirculatory preparation.
Main Results:
- Elevated L-arginine increased perivascular NO by over twofold (411 +/- 42 nM).
- Tissue perfusion increased significantly by 35.5 +/- 7.5% with excess L-arginine.
- Observed variable perivascular PO(2) changes alongside increased perfusion.
Conclusions:
- Increased L-arginine bioavailability directly enhances NO production in the microcirculation.
- This NO increase is associated with improved tissue perfusion.
- Provides direct in vivo evidence for the L-arginine paradox in microvascular regulation.