[ effects of orally administrated magnesium on denuded aorta contractility in streptozotocin induced diabetic rats]

ABSTRACT

Some studies suggest that magnesium deficiency contributes to the cardiovascular complications associated with diabetes mellitus; hence the present study investigated the effects of long term orally administrated magnesium on isolated denuded aorta contractility in response to KCl and Phenylephrine [Phe]. Sixty male Wister rats [180-250 g] were divided into two diabetic and two control groups. One group of each received magnesium sulfate in their drinking water, while the two other groups, had only tap water. After 8 weeks, thoracic aorta was isolated, cut into 2-3 mm rings, endothelium removed and transferred to an organ bath. The tissue was then exposed to cumulative doses of KCl [10, 20, 40, 60 and 80 mM] and Phe [10-9, 10-8, 10-7, 10-6 and 10-5 M] and contractions were measured by an isometric transducer. During the study period, fasting blood samples were obtained every 2 weeks to measure Plasma Glucose level. Vasoconstrictive responses to KCl and Phe were significantly [p<0.05] higher in the control group as compared to the diabetic groups [p<0.05] and there were no significant differences between Mg-treated and non Mg-treated rats. Maximal contractions to KCl were 2.32 +/- 0.23, 2.76 +/- 0.19, 1.96 +/- 0.11 and 1.84 +/- 0.21 and the maximal responses to Phe were 2.94 +/- 0.24, 3.38 +/- 0.20, 2.24 +/- 0.27and 2.61 +/- .27 in the control, Mg-treated control, diabetics and Mg-treated diabetic groups, respectively. No significant differences were found in plasma glucose concentrations between the Mg-treated and non Mg-treated groups. Oral administration of magnesium for 8 weeks has no effect on isolated denuded aorta contractility in diabetic rats