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Vasomotor responses in MnSOD-deficient mice
Jon J Andresen1, Frank M Faraci, Donald D Heistad
1Department of Internal Medicine, University of Iowa, Roy J. and Lucille A. Carver College of Medicine, Iowa City, Iowa 52242, USA.
American Journal of Physiology. Heart and Circulatory Physiology
|August 20, 2004
Summary
Manganese Superoxide Dismutase (MnSOD) deficiency does not alter aortic vasomotor function under normal or oxidative stress conditions. This suggests reduced mitochondrial superoxide may protect nitric oxide bioavailability during stress.
Area of Science:
- Biochemistry
- Physiology
- Cardiovascular Research
Background:
- Manganese Superoxide Dismutase (MnSOD) is essential for mammalian life.
- MnSOD deficient mice exhibit increased susceptibility to oxidative stress.
- Vasomotor function is crucial for regulating blood flow and pressure.
Purpose of the Study:
- To investigate the impact of MnSOD deficiency on aortic vasomotor function.
- To assess responses under normal and induced oxidative stress conditions.
- To explore the role of MnSOD in nitric oxide bioavailability.
Main Methods:
- Comparative analysis of wild-type (WT) and MnSOD(+/-) mouse aortas.
- Assessment of contractile and relaxant responses to various stimuli (serotonin, PGF2alpha, ACh).
- Evaluation of superoxide levels and effects of specific SOD inhibitors (DDC, Tiron) and hypoxia.
Main Results:
- No significant differences in basal vasomotor function or superoxide levels between WT and MnSOD(+/-) aortas.
- Similar impairment of relaxation to ACh and contraction to PGF2alpha by mitochondrial inhibition.
- DDC treatment paradoxically increased contraction and superoxide in WT more than MnSOD(+/-) aortas, with Tiron normalizing responses.
Conclusions:
- Aortic vasomotor function is preserved in MnSOD(+/-) mice under normal and acute oxidative stress.
- Reduced mitochondrial superoxide production in MnSOD deficiency may protect nitric oxide bioavailability.
- Findings suggest compensatory mechanisms in MnSOD-deficient mice regarding vascular function.