Several lines of evidence indicate that reactive oxygen species (ROS) overproduction under the metabolic syndrome condition is the leading cause of cardiovascular events. Calcium is an important stimulus for vasoconstriction and plays a pivotal role in the development of hypertension. Here, we investigate whether a relationship exists between metabolic syndrome-induced mitochondrial ROS overproduction and Ang II-mediated Ca2+ release in vascular smooth muscle cells (VSMC). The effect of mitochondrial ROS on AT1 expression, and Ca2+ and IP3 generation was studied in 2 VSMC models of metabolic syndrome using fura-2/AM probes and ELISA-based assay. Ang II-mediated aortic ring contraction in SD rats fed with high-fat diet (HFD) was measured using a force transducer connected to chart recorder. In the metabolic syndrome, almost 2-fold increased mitochondrial O2 - significantly upregulated AT1 expressions by ~60%, companied by elevated Ca2+ and IP3 levels in VSMC and enhanced aortic rings contraction. All these increments were blocked by rotenone (inhibitor of mitochondrial respiratory chain complex I), ruthenium red (inhibitor of calcium uniporter), cyclosporin A (inhibitor of mitochondrial permeability pore), and N-acetylcysteine. Therefore, in the states of metabolic syndrome, ROS overproduction in mitochondrial complex I enhances Ang II-mediated vascular contraction via an AT1-dependent pathway. In addition, the import of Ca2+ from endoplasmic reticulum to mitochondria via calcium uniporter and mitochondrial permeability pore seems to serve as a mechanism to further aggravate mitochondrial damage and vascular dysfunction that may contribute to the occurrence of hypertension.
The pharmacokinetics and relative bioavailability/bioequivalence of 2 formulations of indapamide were assessed in this paper. The study was conducted in 20 healthy Chinese male volunteers according to an open, randomized, single-blind, 2-way crossover study design with a wash-out phase of 7 days. Blood samples for pharmacokinetic profiling were taken up to 84 h post-dose, and indapamide concentrations in plasma were determined by a validated liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method. Based on the plasma concentration-time data of each individual in each period, pharmacokinetic parameters, Cmax, AUC0-τ, AUC0-∞ and t1/2, were calculated by non-compartmental analysis. Pharmacokinetic parameters for test and reference formulations were analyzed statistically to assess bioequivalence of the 2 formulations. The values of Cmax, Tmax, t1/2, AUC0-τ, AUC0-∞ for test and reference formulations were 49.53±5.53 and 47.79±4.68 ng/mL, 1.9±0.6 and 2.0±0.5 h, 22.49±5.93 and 23.23±4.48 h, 859.51±160.92 and 840.90±170.62 ng · h/mL, 934.35±190.60 and 919.52±179.74 ng · h/mL, respectively. The 90% confidence intervals of the T/R-ratios of logarithmically transformed data were within the accepted range of 80-125%. It showed that the 2 formulations of indapamide were bioequivalent. Both preparations were well tolerated and no adverse reactions were found throughout the study.
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