MAGNESIUM-DEFICIENCY ENHANCES OXIDATIVE STRESS AND COLLAGEN-SYNTHESISIN-VIVO IN THE AORTA OF RATS

Magnesium deficiency has been shown to produce vascular lesions in exp erimental animals, but the underlying mechanisms of vascular injury ar e not clear. It has been reported that in rodents, magnesium deficienc y enhances circulating levels of factors that promote free radical gen eration and are mitogenic, In pursuance of these observations, the pre sent study tested the hypothesis that magnesium deficiency may enhance oxidative stress and trigger an accelerated growth response in vivo i n the aorta of rats. Oxidative stress mas evaluated in terms of levels of thiobarbituric acid-reactive substances in the serum and aorta and activity of superoxide dismutase and catalase in the aorta; fractiona l rates of collagen synthesis were assessed using [H-3]-proline. Serum and tissue levels of magnesium and calcium were determined by atomic absorption spectrophotometry, The present study demonstrated for the f irst time that magnesium deficiency significantly (P < 0.001) increase s levels of thiobarbituric acid-reactive substances in the aorta of ra ts, Other changes in the aorta of animals on the Mg-deficient diet inc luded a significant reduction (54%, P < 0.001) in the activity of supe roxide dismutase and catalase (37%, P < 0.01) and a 19% increase in ne t fractional rates of collagen synthesis (P < 0.05), While serum magne sium was significantly reduced in these animals (P < 0.001), aortic ti ssue levels of magnesium in these animals remained unaltered throughou t the duration of the study, suggesting the existence of other control mechanisms, apart from reduced tissue levels of magnesium, mediating the observed effects. These findings suggest that magnesium deficiency may trigger a wound healing response, involving oxidative injury and growth stimulation, in the vascular system. (C) 1997 Elsevier Science Ltd. All rights reserved.