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Endothelial dysfunction is a hallmark of diabetic vasculopathies. Although hyperglycemia is believed to be the culprit causing endothelial damage, the mechanism underlying early endothelial insult in prediabetes remains obscure. We used a nonobese high-calorie (HC)-fed rat model with hyperinsulinemia, hypercholesterolemia, and delayed development of hyperglycemia to unravel this mechanism. Compared with aortic rings from control rats, HC-fed rat rings displayed attenuated acetylcholinemediated relaxation. While sensitive to nitric oxide synthase (NOS) inhibition, aortic relaxation in HC-rat tissues was not affected by blocking the inward-rectifier potassium (Kir) channels using BaCl 2 . Although Kir channel expression was reduced in HC-rat aorta, Kir expression, endothelium-dependent relaxation, and the BaCl 2 -sensitive component improved in HC rats treated with atorvastatin to reduce serum cholesterol. Remarkably, HC tissues demonstrated increased reactive species (ROS) in smooth muscle cells, which was reversed in rats receiving atorvastatin. In vitro ROS reduction, with superoxide dismutase, improved endothelium-dependent relaxation in HC-rat tissues. Significantly, connexin-43 expression increased in HC aortic tissues, possibly allowing ROS movement into the endothelium and reduction of eNOS activity. In this context, gap junction blockade with 18-b-glycyrrhetinic acid reduced vascular tone in HC rat tissues but not in controls. This reduction was sensitive to NOS inhibition and SOD treatment, possibly as an outcome of reduced ROS influence, and emerged in BaCl 2 -treated control tissues. In conclusion, our results suggest that early metabolic challenge leads to reduced Kir-mediated endotheliumdependent hyperpolarization, increased vascular ROS potentially impairing NO synthesis and highlight these channels as a possible target for early intervention with vascular dysfunction in metabolic disease. SIGNIFICANCE STATEMENTThe present study examines early endothelial dysfunction in metabolic disease. Our results suggest that reduced inwardrectifier potassium channel function underlies a defective endothelium-mediated relaxation possibly through alteration of nitric oxide synthase activity. This study provides a possible mechanism for the augmentation of relatively small changes in one endothelium-mediated relaxation pathway to affect overall endothelial response and highlights the potential role of inwardrectifier potassium channel function as a therapeutic target to treat vascular dysfunction early in the course of metabolic disease.

Aim: To develop a simple HPLC-DAD method for simultaneous determination of febuxostat (FEB) and diclofenac (DIC) in biological samples to assess pharmacokinetic outcomes of their coadministration. Methodology & results: Sample preparation was performed by liquid–liquid extraction. Drugs analysis was done on C18 column using methanol-formic acid pH 2.1 (76:24, v/v) as mobile phase and time-programmed UV detection. Lower limits of quantitation for FEB and DIC were 10 and 20 ng/ml, respectively. Baseline pharmacokinetics were similar to published data on either drug alone. Coadministration led to more than twofold increase in FEB Cmax and AUC together with a reduced hepatic uptake in rats. Conclusion: DIC interfered with initial distribution and terminal clearance of FEB potentially due to reduced FEB hepatic uptake.

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ObjectivesCo-administration of posaconazole (PSZ) and vincristine (VCR) in the treatment of patients with acute lymphoblastic leukemia increases the neurotoxicity of VCR. Our aim is to study the effect of increased lipoprotein levels on the pharmacokinetics of PSZ and VCR upon co-administration in rats.MethodsRats were assigned to three groups, normolipidemic (NL), intermediate hyperlipidemic (IHL), and extreme hyperlipidemic (HL) groups. All rats were administered PSZ orally followed by VCR intravenously 4 h later. For the pharmacokinetic study, serial plasma samples were collected over 96 h and for tissue distribution study; plasma, lung, and liver tissues were collected over 48 h post oral dosing.ResultsPosaconazole showed higher plasma concentrations than VCR at all time points. Co-administration of VCR with PSZ reduced PSZ weight normalized oral clearance, increased PSZ area under the plasma concentration–time curve (AUC) from time zero to infinity, showed higher PSZ liver concentrations, and increased VCR volume of distribution of the central compartment. Upon increasing the lipoprotein levels, PSZ showed higher plasma availability and delayed tissue distribution, whereas VCR had shown a significant decrease in PSZ AUC0-24h, AUC0-tlast, and AUCo-inf (NL = IHL > HL) and a significant increase in the volume of distribution (NL = IHL < HL). Vincristine has shown higher tissue uptake and concentrations.ConclusionMonitoring cholesterol and triglyceride levels in patients with acute lymphoblastic leukemia is advisable to decrease VCR neurological side effect incidences and delay the activity of both PSZ and VCR.