Oral magnesium administration prevents vascular complications in STZ-diabetic rats

Vascular disease is one of the complicating features of diabetes mellitus. Magnesium deficiency has recently been proposed as a novel factor implicated in the pathogenesis of diabetes complications. Several studies have indicated that hypertension in diabetic patients is an independent altered reaction of blood vessels to neurotransmitters and circulating hormones. Since magnesium has been proposed to decrease vascular sensitivity to vasoconstrictor agents, the present study was designed to determine whether chronic magnesium sulfate administration could prevent vascular complications of STZ-induced diabetes in rats. The animals were divided into six groups: two groups served as controls and received tap water for 8 weeks, while in the other four groups, made diabetic with a single IV injection of 40 mg/kg STZ, two groups treated with magnesium sulfate (10 g/L) added to the drinking water, and the other two groups received tap water only. After 8 weeks, in 3 groups (control, diabetic and Mg-treated), left common carotid artery was cannulated for continuous recording of blood pressure. All animals in these groups were decapitated and blood samples were drawn for glucose, Ca and Mg measurements. In the 3 remaining groups (again divided into control, diabetic and Mg-treated), the mesenteric vascular bed was perfused according to the McGregor method, and descending thoracic aortas were used for measurement of elasticity. In diabetic rats, plasma glucose was significantly increased and plasma magnesium was significantly decreased compared to controls and Mg-treated animals. Although plasma magnesium of Mg-treated animals increased significantly, it failed to reach to the magnesium level of the control group. Ca/Mg ratio was also increased compared to the control and Mg-treated animals. Mean arterial blood pressure in diabetics was significantly higher than control and Mg-treated rats. Similarly, there was a significant difference in mean arterial blood pressure of Mg-treated rats compared to control animals. Baseline perfusion pressure of diabetic group was significantly higher than control and Mg-treated groups with intact and denuded endothelium. Magnesium sulfate treatment decreased mean perfusion pressure of mesenteric vascular bed in intact and denuded endothelium in comparison with non-treated diabetic rats. There was a significant increase in passive tension in the aorta of diabetic rats compared to control and Mg-treated rats. However, there was no significant difference between Mg-treated and control rats. From the results of this study it may be concluded that magnesium could control STZ-induced diabetes and prevent its vascular complications.