Down-regulation of Superoxide Dismutase Gene Expression in Cultured Rat Aortic Smooth Muscle Cells (A7r5) after Long-term Incubation with Vitamin C

Liu, Ju-Chi
Chow, Jyh-Ming
Tsai, Min-Feng
Hsieh, Min-Hsiung
Chen, Yi-Jen
Chan, Paul

Department of Medicine, Taipei Medical University-Wan Fang Hospital, Taipei, Taiwan

Received; Accepted

Correspondence: Dr. Paul Chan, MD, PhD. Department of Medicine, Taipei Medical Univeristy-Wan Fang Hospital, No. 111, Hsin-Lung Road, Sec. 3, Wen-Shan, Taipei 117, Taiwan, R.O.C.

Tel: 886-2-2930-7930 ext. 2817; Fax: 886-2-2933-4920

Acta Cardiologica Sinica 16(4):p 209-216, October 2000.

Background:

Oxygen free radicals have been linked to the process of cardiovascular disease and aging. Epidemiological studies supported the beneficial effect of supplementation of antioxidants such as vitamin C and vitamin E. Superoxide dismutase (SOD) is a endogenous enzyme system which can scavenge oxygen free radicals. This study investigated the effect of supplementation of ascorbic acid (vitamin C) on the changes of SOD.

Methods:

Rat aortic smooth muscle cells (A7r5) were divided into 4 groups: a control group (without vitamin C) and treatment groups with vitamin C at 50 μM, 100 μM and 200 μM. After a short-term (2 days) or long-term (7 days) incubation, the enzyme activity and mRNA level of SOD were measured.

Results:

After 7 days incubation, vitamin C resulted in a decrease in the activity and mRNA level of Mn-SOD (mitochondrial enzyme) in a concentration-dependent manner. However, vitamin C supplementation did not change the gene expression and activity of Cu,Zn-SOD (cytosolic enzyme) either after short-term or long-term incubation.

Conclusion:

The results obtained suggest that 7 days incubation with relative high concentrations of vitamin C may down-regulate the gene expression and activity of antioxidant enzyme Mn-SOD in cultured smooth muscle cells.