Diabetes is a leading cause of chronic kidney disease, and the high prevalence of sympathetic nervous system (SNS) hyperactivity in diabetic patients makes them further susceptible to SNS-mediated oxidative stress and accelerated kidney damage. Here, we investigated if canagliflozin can reverse isoprenaline (ISO)-induced renal oxidative damage in rats, a model that mimics SNS overstimulationinduced organ injuries in humans. We found that ISO administration elevates renal oxidative stress markers including malondialdehyde (MDA), advanced protein oxidation product (APOP), myeloperoxidase (MPO) and nitric oxide (NO), while depleting levels of endogenous antioxidants such as catalase (CAT), superoxide dismutase (SOD) and glutathione (GSH). Strikingly, canagliflozin treatment of ISO-treated rats not only prevents elevation of oxidative stress markers but also rescues levels of depleted antioxidants. Our results also show that canagliflozin stimulates antioxidant/antiinflammatory signaling pathways involving AMP-activated protein kinase (AMPK), Akt and eNOS, and inhibits iNOS and NADPH oxidase isoform 4 (NOX4), all of which are associated with oxidative stress and inflammation. Further, canagliflozin prevents ISO-induced apoptosis of kidney cells by inhibiting Bax protein upregulation and caspase-3 activation. Histological examination of kidney sections reveal that canagliflozin attenuates ISO-mediated increases in inflammatory cell infiltration, collagen deposition and fibrosis. Finally, consistent with these findings, canagliflozin treatment improves kidney function in ISO-treated rats, suggesting that the antioxidant effects may be clinically translatable. Diabetic kidney disease is a major risk factor for the development of chronic kidney disease affecting approximately 40% of global diabetic population 1. Diabetic kidney disease is associated with vascular inflammation, loss of renal vascular integrity and hypertension, leading to a progressive loss of renovascular function and renal failure 1. Importantly, there is a high prevalence of sympathetic nervous system (SNS) hyperactivity in diabetic patients associated with autonomic neuropathy and concomitant vagal impairment, making diabetic patients twice as likely to develop hypertension 2. Diabetic patients are also highly susceptible to chronic kidney disease due to renal oxidative damage and inflammation 2. High SNS drive stimulates β1 adrenergic receptors (β1-AR) in juxtaglomerular cells, increasing renin secretion and subsequent activation of the renin-angiotensin-aldosterone system (RAAS). RAAS creates a feed-forward mechanism that accelerates renovascular dysfunction and kidney

The antidiabetic drug canagliflozin is reported to possess several cardioprotective effects. However, no studies have investigated protective effects of canagliflozin in isoprenaline (ISO)-induced cardiac oxidative damage-a model mimicking sympathetic nervous system (SNS) overstimulation-evoked cardiac injuries in humans. Therefore, we investigated protective effects of canagliflozin in ISOinduced cardiac oxidative stress, and their underlying molecular mechanisms in Long-Evans rat heart and in HL-1 cardiomyocyte cell line. Our data showed that ISO administration inflicts pro-oxidative changes in heart by stimulating production of reactive oxygen species (ROS) and reactive nitrogen species (RNS). In contrast, canagliflozin treatment in ISO rats not only preserves endogenous antioxidants but also reduces cardiac oxidative stress markers, fibrosis and apoptosis. Our Western blotting and messenger RNA expression data demonstrated that canagliflozin augments antioxidant and anti-inflammatory signaling involving AMP-activated protein kinase (AMPK), Akt, endothelial nitric oxide synthase (eNOS), nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). In addition, canagliflozin treatment attenuates pro-oxidative, pro-inflammatory and proapoptotic signaling mediated by inducible nitric oxide synthase (iNOS), transforming growth factor beta (TGF-β), NADPH oxidase isoform 4 (Nox4), caspase-3 and Bax. Consistently, canagliflozin treatment improves heart function marker in ISO-treated rats. In summary, we demonstrated that canagliflozin produces cardioprotective actions by promoting multiple antioxidant and antiinflammatory signaling. Canagliflozin, a sodium-glucose cotransporter-2 (SGLT2) inhibitor, belongs to a new class of antidiabetic drugs prescribed for the management of type 2 diabetes mellitus (T2DM) 1. Accumulating evidence suggests that canagliflozin exhibits a range of cardiovascular effects that are independent of glucose lowering. According to recent preclinical and clinical data, canagliflozin treatment significantly reduced risk of cardiovascular death, myocardial infarction (MI), stroke and hospitalization due to heart failure in both diabetic and non-diabetic subjects 2-5. Proposed mechanisms for cardiovascular benefits of canagliflozin include improvement of cardiac metabolism and diastolic function, reduction of vascular stiffness, and an overall reduction of blood pressure 5-9. A growing body of evidence suggests that canagliflozin possess antioxidant and anti-inflammatory actions in various cellbased and animal models 10-14. Canagliflozin was shown to reduce vascular inflammation and atherosclerosis by

No abstract

No abstract

Long‐term use of simvastatin, an inhibitor HMG‐CoA reductase and cholesterol synthesis, has been reported to influence vascular function secondary to the reduction of cholesterol. However, direct effects of simvastatin application on fresh isolated arteries and its relevance for arterial contractility regulation are unclear. Here, we investigated direct regulation of vascular reactivity by therapeutic concentrations of simvastatin in an ex‐vivo preparation of rat thoracic aorta using a combination of wire myography, Western blotting, and arterial biotinylation techniques. Our wire myography data revealed that simvastatin stimulates reversible contraction of aorta at therapeutic concentrations (0.0001–0.1 μM), with 0.01 μM producing maximum response that is equivalent to ~60% of depolarization‐mediated aorta contraction induced by 60mM K+. Endothelium removal or co‐application of mevalonate with simvastatin did not alter simvastatin‐induced vasocontraction. In contrast, removing extracellular Ca2+ with EGTA or co‐application of nimodipine, a blocker of CaV1.2, each abolished simvastatin‐evoked contraction of aorta. Ryanodine, a blocker of ryanodine receptor‐mediated Ca2+ release from intracellular Ca2+ stores, did not alter aorta contraction by simvastatin. Arterial biotinylation data showed that CaV1.2 channel protein expression and relative cellular distribution remain unchanged by simvastatin for the time points covering duration of simvastatin application. In summary, our data suggest that simvastatin directly controls arterial smooth muscle cell [Ca2+]i and arterial contractility primarily by stimulating Ca2+ entry via CaV1.2 ion channel in arterial smooth muscle cells, which is independent of HMG‐CoA reductase inhibition by simvastatin. Our future studies will examine if simvastatin and other statins can alter arterial contractility and blood pressure in normotensive and hypertensive animals in which CaV1.2 is upregulated. Support or Funding Information This work was supported by a start‐up grant from the Mercer University College of Pharmacy to Dr. Raquibul Hasan