The variation of macro- and micro-minerals of tissues in diabetic and non-diabetic rats.

This study determined the levels of Ca, Mg, Fe, Zn, Cu, and Na in various tissues samples (liver, brain, kidney, intestines, muscle and hair) of diabetic and non-diabetic rats by flame atomic absorption spectroscopy, in order to assess the role of element levels during T2DM. The ratios of Ca/Mg, Zn/Cu, Ca/Zn, and Mg/Zn in diabetic and non-diabetic rat tissues were also calculated. The determined element levels were further subjected to a student-t test statistical analysis and multiple-linear-regression in order to evaluate similarities, differences, and an inter-element association in tissues of diabetic and non-diabetic rats. The results of the study showed high variability in element levels and Ca/Mg Zn/Cu Mg/Zn Ca/Zn ratios in the tissues of diabetic and non-diabetic rats, but are tissue- and element-dependent, suggesting differences in the accumulation of the elements in tissues of diabetics and non-diabetics. The obtained significant differences in the levels of elements and Ca/Mg Zn/Cu Mg/Zn Ca/Zn ratios in several tissues of diabetic and non-diabetic rats in this study suggest that the investigated elements play considerable roles in the T2DM disease process. Strong inter-element associations (R2≥0.9) were observed for some elements in tissues of diabetic and non-diabetics rats. However, poor inter-elemental associations were obtained for some elements in the tissues of diabetic and non-diabetic rats.

Increased constrictor tone induced by ouabain treatment in rats.

Ouabain (Oua)-induced hypertension in rodents provides a model to study cardiovascular changes associated with human hypertension. We examined vascular function in rats after a long-term treatment with Oua. Systolic blood pressure was measured by tail-cuff plethysmography in male Sprague-Dawley rats treated with Oua (≈ 25 µg/d) or placebo for 8 weeks. Blood pressure increased in Oua-treated animals, reaching 30% above baseline systolic blood pressure after 7 weeks. At the end of treatment, vascular responses were studied in mesenteric resistance arteries (MRAs) by wire myography. Contraction to potassium chloride in intact and denuded arteries showed greater sensitivity in Oua-treated animals. Contraction to phenylephrine and relaxation to acetylcholine were similar between groups with a lower response to sodium nitroprusside in Oua-treated arteries. Sensitivity to endothelin-1 was higher in Oua-treated arteries. Na⁺-K⁺ ATPase activity was decreased in MRAs from Oua-treated animals, whereas protein expression of the Na⁺-K⁺ ATPase α2 isoform was increased in heart and unchanged in mesenteric artery. Preincubation with indomethacin (10⁻5 M) or Nω-nitro-L-arginine methyl ester (10⁻4 M) abolished the differences in potassium chloride response and Na⁺-K⁺ ATPase activity. Changes in MRAs are consistent with enhanced vascular smooth muscle cell reactivity, a contributor to the increased vascular tone observed in this model of hypertension.