Increase In Glucose Excretion Research Articles

Demystifying the results obtained through the use of SGLT-2 inhibitor drugs, used by patients at the Reference Center for Hypertension and Diabetes Rio Verde - Goiás

Introduction: Due to the increase in glucose excretion of renal sodium-glucose cotransporter 2 (ISGLT-2) inhibitors, there is also a reduction in weight through its glycosuric effect. Objective: To analyze the efficacy of ISGLT-2 based on medical records and glycemic levels according to glycated blood glucose; to verify which medications are most prescribed and to observe poor adherence due to side effects in patients of the CRHD in Rio Verde-GO. Methods: A descriptive observational study was carried out using the medical records of diabetic patients treated at the CRHD as the main means of data collection, identifying and comparing laboratory values based on the different pharmacological conducts performed. And manually organize and group the search results on the Excel platform, where they will later be converted into easy-to-view graphs for the public. Results And Discussion: When analyzing the glycated hemoglobin (HbA1c) of the patients before and after the introduction of the ISGLT-2 class, it was noted that 80% obtained a laboratory improvement and 20% a worsening. The results reveal that 80% had an improvement in glycated hemoglobin, as they presented good adherence to the medication and specific and balanced nutrition for their condition. Conclusion: There is an improvement in glycated hemoglobin in most of the patients treated at the CRHD who are users of iSGLT-2, where the most used medication is Forxiga (Dapaglifozin), which is part of the medications of the SUS network.

PERIOPERATIVE DIABETIC KETOACIDOSIS ASSOCIATED WITH SODIUM-GLUCOSE CO-TRANSPORTER-2 INHIBITORS : A SYSTEMATIC REVIEW

DKA or diabetic ketoacidosis is an emergency condition caused by hyperglycemia in which excessive acid is produced in the blood. Patients with type 1 and type 2 diabetes who undergo surgery, have an infection, or are under extreme stress can also develop DKA. The body generates the hormone adrenaline to combat infection and stress, but this can have a negative effect on blood glucose levels (adrenaline is counterinsulin). This can worsen if the patient refuses to take diabetes medication or inject insulin during stressful or infectious situations. The fundamental components of the pathophysiological mechanisms at play in diabetic ketoacidosis (DKA) include shifts in hormone levels and the ensuing inflammatory response. Alterations in the concentration of hormones lead to shifts in the production and consumption of glucose, as well as an increase in lipolysis and the formation of ketone bodies. Canagliflozin, dapagliflozin, empagliflozin, and ertugliflozin are agents approved by the Food and Drug Administration (FDA) for the treatment of type 2 diabetes mellitus (DM) in adults. Acting on proteins, the four agents are SGLT2 inhibitor class agents. SGLT-2 is expressed in the kidney's proximal tubule. This may result in a decrease in filtered glucose reabsorption, a decrease in the renal threshold for glucose (RTG), and an increase in glucose excretion via urine. Diabetes patients treated with sodium–glucose transport protein 2 (SGLT2) inhibitors have also been reported to experience DKA. The results of a study indicate that DKA is uncommon among T2DM patients treated with SGLT2 inhibitors.

Dapagliflozin efficacy as an add-on therapy in double and triple-drug regimens: A meta-analysis of randomized control trial

Background: Diabetes is one of the most common diseases compared to others. There are many drugs available in the market to treat diabetes. Still, most of them have adverse drug reactions like hypoglycemia, weight gain, and subtherapeutic drug concentrations. SGLT-2 inhibitors are a new class of drugs used as add-on therapy to treat type-2 Diabetes Mellitus. They act by inhibiting glucose reabsorption and increasing glucose excretion via the kidneys. In an average adult, two kidneys filter about 180g of glucose per day. About 98% of the glucose filtered in the kidneys get reabsorbed in the proximal convoluted tubule back into the bloodstream, which can be inhibited by SGLT-2 inhibitors.
 Method: A systematic review and meta-analysis were performed on randomized clinical trial data, extracted from PubMed, Cochrane and Embase. All data, including baseline and shift of baseline, standard deviation, and number of participants, were recorded for HbA1c, Fasting blood glucose (FBG), Bodyweight and SBP/DBP.
 Results: Twelve randomized clinical trials, including 8000 participants, were compared and divided into three groups of drugs: SAXA+DAPA+MET, SAXA+MET and DAPA+MET. The comparison is done for HbA1c (WMD:-6.78; 95% CI:-8.28; P <0.00001) (WMD:-4.88; 95% CI:-6.93; P <0.00001), FBG (SMD: -6.50; 95% CI: -8.55, -4.45; P <0.00001) (SMD: -7.75; 95% CI: -8.84, -6.66; P<0.00005,), body weight (SMD: 0.30; 95% CI: 0.27, 0.33; P =1.00) (SMD: -1.00; 95% CI: -1.90, -0.10; P<0.00001). Conclusion: Dapagliflozin, when given in combination, shows a major improvement in HbA1c and FBG levels and does not affect body weight. It was shown to be more effective when given in triple combination therapy.
 Keywords: Dapagliflozine, meta-analysis, Sexagliptine, Metformin, Type two diabetes mellitus (T2DM), Sodium-glucose Cotransporter-2 (SGLT2)

The ratio of free triiodothyronine to free thyroxine is regulated differently in patients with type 2 diabetes mellitus treated and not treated with sodium glucose cotransporter 2 inhibitors

Background and aimsTriiodothyronine reduces sodium glucose cotransporter 2 expression in the kidney and increased glucose excretion in urine of alloxan-induced diabetic rats. Free thyroxine is also negatively associated with islet beta-cell function in euthyroid subjects. However, the influence of sodium glucose cotransporter 2 inhibitor on thyroid function in patients with type 2 diabetes mellitus has not been established. MethodsWe investigated thyroid function in patients with type 2 diabetes mellitus in the presence or absence of sodium glucose cotransporter 2 inhibitor in a multicenter retrospective study conducted between 2019 and 2021. All participants visited the hospital monthly for type 2 diabetes mellitus treatment and plasma glucose and glycated hemoglobin level measurements. Furthermore, thyroid-stimulating hormone, free triiodothyronine, and free thyroxine levels were measured annually. ResultsFree triiodothyronine level and the free triiodothyronine:free thyroxine ratio in the group treated with sodium glucose cotransporter 2 inhibitor were significantly higher than the levels in the group not treated with sodium glucose cotransporter 2 inhibitor. Free triiodothyronine levels in the group treated with sodium glucose cotransporter 2 inhibitor were significantly higher than the levels in the group not treated with sodium glucose cotransporter 2 inhibitor (p = 0.040). Free thyroxine levels in the group treated with sodium glucose cotransporter 2 inhibitor were significantly lower than the levels in the group not treated with sodium glucose cotransporter 2 inhibitor (p = 0.002). Thyroid-stimulating hormone levels did not differ significantly between the two groups. ConclusionsOur findings show that sodium glucose cotransporter 2 inhibitor affects free triiodothyronine levels free thyroxine levels, and the free triiodothyronine:free thyroxine ratio.

Cardioprotection by selective SGLT-2 inhibitors in a non-diabetic mouse model of myocardial ischemia/reperfusion injury: a class or a drug effect?

Major clinical trials with sodium glucose co-transporter-2 inhibitors (SGLT-2i) exhibit protective effects against heart failure events, whereas inconsistencies regarding the cardiovascular death outcomes are observed. Therefore, we aimed to compare the selective SGLT-2i empagliflozin (EMPA), dapagliflozin (DAPA) and ertugliflozin (ERTU) in terms of infarct size (IS) reduction and to reveal the cardioprotective mechanism in healthy non-diabetic mice. C57BL/6 mice randomly received vehicle, EMPA (10mg/kg/day) and DAPA or ERTU orally at the stoichiometrically equivalent dose (SED) for 7days. 24h-glucose urinary excretion was determined to verify SGLT-2 inhibition. IS of the region at risk was measured after 30min ischemia (I), and 120min reperfusion (R). In a second series, the ischemic myocardium was collected (10th min of R) for shotgun proteomics and evaluation of the cardioprotective signaling. In a third series, we evaluated the oxidative phosphorylation capacity (OXPHOS) and the mitochondrial fatty acid oxidation capacity by measuring the respiratory rates. Finally, Stattic, the STAT-3 inhibitor and wortmannin were administered in both EMPA and DAPA groups to establish causal relationships in the mechanism of protection. EMPA, DAPA and ERTU at the SED led to similar SGLT-2 inhibition as inferred by the significant increase in glucose excretion. EMPA and DAPA but not ERTU reduced IS. EMPA preserved mitochondrial functionality in complex I&II linked oxidative phosphorylation. EMPA and DAPA treatment led to NF-kB, RISK, STAT-3 activation and the downstream apoptosis reduction coinciding with IS reduction. Stattic and wortmannin attenuated the cardioprotection afforded by EMPA and DAPA. Among several upstream mediators, fibroblast growth factor-2 (FGF-2) and caveolin-3 were increased by EMPA and DAPA treatment. ERTU reduced IS only when given at the double dose of the SED (20mg/kg/day). Short-term EMPA and DAPA, but not ERTU administration at the SED reduce IS in healthy non-diabetic mice. Cardioprotection is not correlated to SGLT-2 inhibition, is STAT-3 and PI3K dependent and associated with increased FGF-2 and Cav-3 expression.

IDF21-0310 A real-world clinical experience on effectiveness of remogliflozin etabonate in management of Indian patients with T2DM

Background: Type 2 diabetes (T2DM) is a multifactorial chronic disease with a complex pathophysiology. A variety of antidiabetic treatment options are available, however Sodium-glucose co-transporter-2 inhibitors (SGLT2i) assist in decreasing body weight by increasing glucose excretion and insulin sensitivity, reduction in blood pressure and arterial stiffness and can act as adjuvant to other antidiabetic drugs. Remogliflozin etabonate (RE) is a potent and selective SGLT2i recently approved in India for the treatment of patients with T2DM.

Therapeutic Interventions of Novel SGLT2 Inhibitors Against Metabolic Disorders: Transforming the Association into Perspectives.

Sodium-glucose co-transporter 2 (SGLT2) inhibitors are an emerging group of therapeutic agents that show their tremendous glucose lowering activity without producing hypoglycemia, which is one of the major drawbacks of existing antidiabetic therapy. Comprehensive literature was searched in English using electronic databases including PubMed, ScienceDirect, Medline, Scopus and Embase. SGLT2 inhibitors reduce blood glucose levels by producing glucosuria via insulin-independent pathway. The major mechanism by which SGLT2 inhibitors are involved in glucose homeostasis is to prevent the reabsorption of glucose in the proximal convoluted tubule and increase glucose excretion in the urine. Deterioration of β-cells, impairment of functions and development of insulin resistance do not affect the efficacy of SGLT2 inhibitors. SGLT2 inhibitors significantly reduce HbA1c, ameliorate glycemic control and control body weight. SGLT2 inhibitors can block Na+/H+ exchanger (NHE) 1 and play a significant role in treatment of heart failure especially in diabetic patients. They have also positive effects on different metabolic syndromes which cumulatively ameliorate the risk factors for cardiovascular diseases in diabetic patients. SGLT2 inhibitors can improve kidney function by reducing inflammation and improving renal microvasculature up to its original state. The increase in triglyceride level has a strong relationship with coronary artery disease in diabetic patients when combined with other indicators of metabolic disorders while SGLT2 inhibitors cause a significant reduction in plasma triglyceride level in diabetic patients. We have comprehensively summarized the features, mechanism of action of SGLT2 inhibitors and their impact on various metabolic syndrome traits, including diabetic condition, renal dysfunctioning, arterial stiffness, hypertension, lipid profile and cardiovascular diseases. The aim of this review to examine the safety, efficacy and therapeutic properties of SGLT2 inhibitors in renal and diabetic patients.

Gliflozins for the Treatment of Congestive Heart Failure and Renal Failure in Type 2 Diabetes.

Gliflozins are effective drugs for the treatment of type 2 diabetes. They inhibit sodium glucose cotransporter 2 in the proximal renal tubule, leading to increased glucose excretion. On the basis of findings from relevant studies, gliflozins are also increasingly used in clinical practice to treat congestive heart failure and renal failure. This review is based on pertinent publications retrieved from a selective literature search in PubMed and GoogleScholar. Cardiovascular safety studies revealed early on that gliflozins can lower the hospitalization rate of patients suffering from congestive heart failure with a reduced leftventricular ejection fraction (HFrEF). They also showed favorable effects on multiple renal endpoints. In recent years, studies such as DAPA-HF and CREDENCE have further documented the benefit of gliflozins in the treatment of congestive heart failure and renal failure in patients with type 2 diabetes, and gliflozins have accordingly been incorporated into the pertinent guidelines. In the recently published EMPEROR-Reduced trial, empagliflozin was found to significantly lower the frequency of a combined cardiovascular endpoint in patients with HFrEF (19.4 % versus 24.7%; hazard ratio [HR] 0.75; 95% confidence interval [0.65; 0.86]; number needed to treat [NNT] 19, p <0.001). In the DAPA-CKD trial, which was also recently published, dapagliflozin was found to significantly lower the frequency of a combined renal endpoint (9.2% versus 14.5%; HR 0.61 [0.51; 0.72]; NNT 19; p <0.001). On the basis of findings from specific studies, gliflozins will henceforth be a major class of drug for the treatment of HFrEF and renal failure, independently of the presence of type 2 diabetes.

Antidiabetic drug therapy alleviates type 1 diabetes in mice by promoting pancreatic α-cell transdifferentiation

Gut incretins, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP), enhance secretion of insulin in a glucose-dependent manner, predominantly by elevating cytosolic levels of cAMP in pancreatic β-cells. Successful targeting of the incretin pathway by several drugs, however, suggests the antidiabetic mechanism is likely to span beyond the acute effect on hormone secretion and include, for instance, stimulation of β-cell growth and/or proliferation. Likewise, the antidiabetic action of kidney sodium-glucose linked transporter-2 (SGLT-2) inhibitors exceeds simple increase glucose excretion. Potential reasons for these ‘added benefits’ may lie in the long-term effects of these signals on developmental aspects of pancreatic islet cells. In this work, we explored if the incretin mimetics or SGLT-2 inhibitors can affect the size of the islet α- or β-cell compartments, under the condition of β-cell stress.To that end, we utilised mice expressing YFP specifically in pancreatic α-cells, in which we modelled type 1 diabetes by injecting streptozotocin, followed by a 10-day administration of liraglutide, sitagliptin or dapagliflozin.We observed an onset of diabetic phenotype, which was partially reversed by the administration of the antidiabetic drugs. The mechanism for the reversal included induction of β-cell proliferation, decrease in β-cell apoptosis and, for the incretin mimetics, transdifferentiation of α-cells into β-cells.Our data therefore emphasize the role of chronic incretin signalling in induction of α-/β-cell transdifferentiation. We conclude that incretin peptides may act directly on islet cells, making use of the endogenous local sites of ‘ectopic’ expression, whereas SGLT-2 inhibitors work via protecting β-cells from chronic hyperglycaemia.

P0950EFFECT OF THYROID HORMONE TREATMENT ON RENAL REABSORPTION OF GLUCOSE IN ALLOXAN-INDUCED DIABETIC RATS

Abstract Background and Aims The thyroid hormone (TH) plays an important role in glucose metabolism. Recently, we showed that the TH improves glycemia control by decreasing cytokines expression in the adipose tissue and skeletal muscle of alloxan-induced diabetic rats, which were also shown to present primary hypothyroidism. In this context, this study aims to investigate whether the chronic treatment of diabetic rats with T3 could affect other tissues that are involved in the control of glucose homeostasis, as the liver and kidney. Method Adult male Wistar rats were divided into nondiabetic, diabetic, and diabetic treated with T3 (1.5 ?g/100 g BW for 4 weeks). Diabetes was induced by alloxan monohydrate (150 mg/kg, BW, i.p.). Animals showing fasting blood glucose levels greater than 250 mg/dL were selected for the study. Results After treatment, we measured the blood glucose, serum T3, T4, TSH, and insulin concentration, hepatic glucose production by liver perfusion, liver PEPCK, GAPDH, and pAKT expression, as well as urine glucose concentration and renal expression of SGLT2 and GLUT2. T3 reduced blood glucose, hepatic glucose production, liver PEPCK, GAPDH, and pAKT content and the renal expression of SGLT2 and increased glycosuria. Conclusion Results suggest that the decreased hepatic glucose output and increased glucose excretion induced by T3 treatment are important mechanisms that contribute to reduce serum concentration of glucose, accounting for the improvement of glucose homeostasis control in diabetic rats.

Long-term empagliflozin therapy improves levels of hepatic fibrosis marker in patients with non-alcoholic fatty liver disease complicated by type 2 diabetes mellitus

The long-term outcomes of patients with non-alcoholic fatty liver disease (NAFLD) treated with sodium-glucose cotransporter-2 inhibitors remain indeterminate. Empagliflozin improves hyperglycemia by increasing glucose excretion in the urine, and it reduces fat volume and insulin resistance. The aim of this study is to assess the effect of long-term empagliflozin therapy on hepatic inflammation, function and fibrosis in patients with NAFLD. This is a two-center retrospective observational study including patients with NAFLD complicated by type 2 diabetes mellitus. We retrospectively reviewed the medical records. Changes in parameters were investigated over one-year empagliflozin treatment. Twenty-four patients treated with empagliflozin were evaluated. Weight, body mass index, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transpeptidase, fasting plasma glucose, hemoglobin A1c, serum insulin and homeostasis model assessment insulin resistance significantly decreased during treatment (p < 0.05). Albumin-bilirubin (ALBI) score, a marker of hepatic function, was significantly improved (p < 0.01). The FIB-4 index and Mac-2 Binding Protein Glucosylation Isomer, markers of hepatic fibrosis, significantly improved (p < 0.01). One-year empagliflozin treatment of patients with NAFLD complicated by type 2 diabetes mellitus significantly improves markers of hepatic inflammation, function and fibrosis. J. Med. Invest. 67 : 280-284, August, 2020.

Empagliflozin reverses obesity and insulin resistance through fat browning and alternative macrophage activation in mice fed a high-fat diet

ObjectiveWe reported previously that empagliflozin—a sodium-glucose cotransporter (SGLT) 2 inhibitor—exhibited preventive effects against obesity. However, it was difficult to extrapolate these results to human subjects. Here, we performed a therapeutic...

8-Aminoguanine Induces Diuresis, Natriuresis, and Glucosuria by Inhibiting Purine Nucleoside Phosphorylase and Reduces Potassium Excretion by Inhibiting Rac1.

Background8‐Aminoguanosine and 8‐aminoguanine are K+‐sparing natriuretics that increase glucose excretion. Most effects of 8‐aminoguanosine are due to its metabolism to 8‐aminoguanine. However, the mechanism by which 8‐aminoguanine affects renal function is unknown and is the focus of this investigation.Methods and ResultsBecause 8‐aminoguanine has structural similarities with inhibitors of the epithelial sodium channel (ENaC), Na+/H+ exchangers, and adenosine A1 receptors, we examined the effects of 8‐aminoguanine on ENaC activity in mouse collecting duct cells, on intracellular pH of human proximal tubular epithelial cells, on responses to a selective A1‐receptor agonist in vivo, and on renal excretory function in A1‐receptor knockout rats. These experiments showed that 8‐aminoguanine did not block ENaC, Na+/H+ exchangers, or A1 receptors. Because Rac1 enhances activity of mineralocorticoid receptors and some guanosine analogues inhibit Rac1, we examined the effects of 8‐aminoguanine on Rac1 activity in mouse collecting duct cells. Rac1 activity was significantly inhibited by 8‐aminoguanine. Because in vitro 8‐aminoguanine is a purine nucleoside phosphorylase (PNPase) inhibitor, we examined the effects of a natriuretic dose of 8‐aminoguanine on urinary excretion of PNPase substrates and products. 8‐Aminoguanine increased and decreased, respectively, urinary excretion of PNPase substrates and products. Next we compared in rats the renal effects of intravenous doses of 9‐deazaguanine (PNPase inhibitor) versus 8‐aminoguanine. 8‐Aminoguanine and 9‐deazaguanine induced similar increases in urinary Na+ and glucose excretion, yet only 8‐aminoguanine reduced K+ excretion. Nsc23766 (Rac1 inhibitor) mimicked the effects of 8‐aminoguanine on K+ excretion.Conclusions8‐Aminoguanine increases Na+ and glucose excretion by blocking PNPase and decreases K+ excretion by inhibiting Rac1.

Abstract 067: Mechanism of Action of 8-Aminoguanine on Renal Excretory Function

The endogenous purines 8-aminoguanosine and 8-aminoguanine (8-AG) are K + -sparing natriuretics that increase glucose excretion and attenuate salt-induced hypertension. Most effects of 8-aminoguanosine are not direct, but require conversion in the systemic circulation to 8-AG (i.e., 8-aminoguanosine is a prodrug/prohormone). However, the mechanism of action by which 8-AG affects renal excretory function is unknown and is the subject of this investigation. Because 8-AG has structural similarities with inhibitors of epithelial Na + channels (ENaC), Na + /H + exchangers (NHE), and adenosine A 1 receptors, we examined the effects of 8-AG on amiloride-sensitive ENaC activity in mouse collecting duct cells, on intracellular pH of human renal proximal tubule epithelial cells, and on in vivo (in rats) pharmacological responses to 2-chloro-N 6 -cyclopentyladenosine (A 1 -receptor agonist). 8-AG did not block ENaC, NHE, or A 1 receptors. Because Rac1 enhances activity of mineralocorticoid receptors and some guanosine analogues inhibit Rac1, we examined the effects of 8-AG on Rac1 activity in mouse collecting duct cells. Rac1 activity was significantly ( P =0.024) inhibited by 8-AG (30 μM; from 2.5 ± 0.7 to 1.7 ± 0.7 arbitrary units). Because 8-AG is an inhibitor of purine nucleoside phosphorylase (PNPase; metabolizes inosine to hypoxanthine and guanosine to guanine), we compared the renal effects (in rats) of approximately equipotent intravenous doses of 8-AG (33.5 μmol/kg) vs. 9-deazaguanine (9-DG; 67 μmol/kg; PNPase inhibitor). 8-AG and 9-DG induced similar increases in urinary Na + (μmol/30 min; 8-AG, from 4.4 ± 2.0 to 38 ± 17; 9-DG, from 5.6 ± 3.3 to 34 ± 8.6) and glucose (μg/30 min; 8-AG, from 31 ± 17 to 225 ± 77; 9-DG, from 6.9 ± 3.9 to 144 ± 81) excretion. Intravenous 8-AG increased urinary excretion of guanosine and inosine (PNPase substrates), yet decreased excretion of guanine and hypoxanthine (PNPase products). 8-AG reduced K + excretion (μmol/30 min; 8-AG, from 29 ± 6.6 to 5.4 ± 1.7) whereas 9-DG did not. However, the Rac1 inhibitor Nsc23766 (9.4 μmol/kg) mimicked the effects of 8-AG on K + excretion (μmol/30 min; from 40 ± 7.1 to 18 ± 6.5). Conclusion: Likely 8-AG increases Na + and glucose excretion by blocking PNPase and decreases K + excretion by inhibiting Rac1.

Risks Associated with SGLT2 Inhibitors: An Overview.

Sodium glucose co-transport 2 inhibitors (SGLT2-i) are the new class of antidiabetic medications which are recently approved (2013) by the Food and Drug Administration (FDA) for the treatment of diabetes. These inhibitors block the SGLT2 protein which involved glucose reabsorption from proximal renal tubule resulting in increased glucose excretion and lower blood glucose levels. These inhibitors exert favourable effects beyond glucose control such as consistent body weight, blood pressure and serum uric acid reductions. Canagliflozin, Dapagliflozin and empagliflozin belong to the class of SGLT2 inhibitors. All these drugs are giving promising results in the treatment of diabetes mellitus, but emerging data from post-marketing studies indicate their adverse effects such as diabetic ketoacidosis, genital and urinary tract infection, cancer, bone fracture and foot and leg amputation. Thus, there is a need for better understanding the risk profile of SGLT2 inhibitors. In this review, we have compiled the risk profile of SGLT2 inhibitors by collecting information from various sources such as case reports, published literature and from various regulatory websites. Further, the proposed mechanism of risks has also been discussed.

Effects of the sodium-glucose cotransporter 2 (SGLT2) inhibitor velagliflozin, a new drug with therapeutic potential to treat diabetes in cats.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are used in the treatment of human diabetics. They increase glucose excretion and correct hyperglycemia. We examined the investigational SGLT2 inhibitor velagliflozin in two groups of six neutered adult obese cats (equal gender distribution). Placebo (Pl) or drug (D; 1mg/kg) was administered for 35days. Routine blood examinations, fructosamine, beta-hydroxybutyrate (BHB), nonesterified fatty acids (NEFA), glucagon, adiponectin, and leptin were measured before and after treatment, also water intake, and urinary electrolytes, glucose, and volume. Indirect calorimetry, an intravenous glucose tolerance test (IVGTT; 0.8g/kg) and insulin tolerance test (IVITT) were conducted. All cats tolerated treatment well. Significant changes with D included a decrease in the respiratory exchange ratio, an increase in cholesterol, a small increase in albumin, and a rise in BHB and NEFA. Glucose clearance was unaltered, although less insulin was secreted during the IVGTT (p=.056) suggesting improved insulin sensitivity. IVITT was unchanged. Treatment did not affect glucagon, leptin, or adiponectin. Water intake, urine output, urinary glucose excretion, and the glucose/creatinine ratio but not urinary electrolytes were significantly higher post-D. We conclude that velagliflozin is a promising drug, which increases urinary glucose excretion in cats and could thereby be beneficial for the treatment of hyperglycemia.

8-Aminoguanosine and 8-Aminoguanine Exert Diuretic, Natriuretic, Glucosuric, and Antihypertensive Activity.

In vivo, guanine moieties in DNA, RNA, guanine nucleotides, or guanosine or guanine per se can undergo nitration (for example, by peroxynitrite) or hydroxylation (for example, by superoxide anion) on position 8 of the purine ring. Subsequent catabolism of these modified biomolecules leads to the production of a diverse group of 8-nitro, 8-amino, and 8-hydroxy guanosine and guanine compounds. Indeed, studies suggest the in vivo existence of 8-nitroguanosine, 8-nitroguanine, 8-aminoguanosine, 8-aminoguanine, 8-hydroxyguanosine, 8-hydroxy-2'-deoxyguanosine, and 8-hydroxyguanine. Since a multitude of these compounds exist in vivo, and since the renal effects of 8-substituted guanosine and guanine compounds are entirely unknown, we examined the effects of guanosine, guanine, 8-nitroguanosine, 8-nitroguanine, 8-hydroxyguanosine, 8-hydroxyguanine, 8-hydroxy-2'-deoxyguanosine, 8-aminoguanosine, and 8-aminoguanine (33.5 µmol/kg/min; intravenous infusion for 115 minutes) on excretion of sodium, potassium, and glucose in rats. Guanosine, 8-nitroguanosine, and 8-hydroxy-2'-deoxyguanosine had minimal natriuretic activity. Guanine, 8-nitroguanine, 8-hydroxyguanosine, and 8-hydroxyguanine had moderate natriuretic activity (increased sodium excretion by 9.4-, 7.8-, 7.1-, and 8.6-fold, respectively). In comparison with all other compounds, 8-aminoguanosine and 8-aminoguanine were highly efficacious and increased sodium excretion by 26.6- and 17.2-fold, respectively, exceeding that of a matched dose of amiloride (13.6-fold increase). 8-Aminoguanosine and 8-aminoguanine also increased glucose excretion by 12.1- and 12.2-fold, respectively, and decreased potassium excretion by 69.1 and 71.0%, respectively. Long-term radiotelemetry studies demonstrated that oral 8-aminoguanosine and 8-aminoguanine (5 mg/kg/day) suppressed deoxycorticosterone/salt-induced hypertension. These experiments demonstrate that some naturally occurring 8-substitued guanosine and guanine compounds, particularly 8-aminoguanosine and 8-aminoguanine, are potent and efficacious potassium-sparing diuretics/natriuretics that may represent a novel class of antihypertensive diuretics.

Dapagliflozin Binds Specifically to Sodium-Glucose Cotransporter 2 in the Proximal Renal Tubule.

Kidneys contribute to glucose homeostasis by reabsorbing filtered glucose in the proximal tubules via sodium-glucose cotransporters (SGLTs). Reabsorption is primarily handled by SGLT2, and SGLT2-specific inhibitors, including dapagliflozin, canagliflozin, and empagliflozin, increase glucose excretion and lower blood glucose levels. To resolve unanswered questions about these inhibitors, we developed a novel approach to map the distribution of functional SGLT2 proteins in rodents using positron emission tomography with 4-[18F]fluoro-dapagliflozin (F-Dapa). We detected prominent binding of intravenously injected F-Dapa in the kidney cortexes of rats and wild-type and Sglt1-knockout mice but not Sglt2-knockout mice, and injection of SGLT2 inhibitors prevented this binding. Furthermore, imaging revealed only low levels of F-Dapa in the urinary bladder, even after displacement of kidney binding with dapagliflozin. Microscopic ex vitro autoradiography of kidney showed F-Dapa binding to the apical surface of early proximal tubules. Notably, in vivo imaging did not show measureable specific binding of F-Dapa in heart, muscle, salivary glands, liver, or brain. We propose that F-Dapa is freely filtered by the kidney, binds to SGLT2 in the apical membranes of the early proximal tubule, and is subsequently reabsorbed into blood. The high density of functional SGLT2 transporters detected in the apical membrane of the proximal tubule but not detected in other organs likely accounts for the high kidney specificity of SGLT2 inhibitors. Overall, these data are consistent with data from clinical studies on SGLT2 inhibitors and provide a rationale for the mode of action of these drugs.

Abstract P138: Targeted Disruption of Regulated Endocrine Specific Protein ( Resp18 ) in Dahl SS Rats Increases Blood Pressure and Renal Injury

Essential hypertension is a complex polygenic trait. To understand the genetics of Blood pressure (BP) control, loci are mapped using populations derived by crossing several rat strains with the genetically hypertensive rat model, the Dahl SS rat (SS) and validated as BP quantitative trait loci (QTL). Genes located within the mapped BP QTLs are candidates as inherited loci controlling BP, but require further proof. One such mapped locus is on rat chromosome 9, wherein the proof for one of the candidate genes Regulated Endocrine Specific Protein-18 ( Resp18 ), as a BP QTL, is currently inadequate. To ascertain the status of Resp18 as a BP QTL, a custom targeted gene disruption model of Resp18 was developed on the SS background. As a result of this ZFN mediated disruption, a 7 bp deletion occurred within exon 3 of the Resp18 locus, resulting in a truncated protein with 111aa compared to the full length protein consisting of 175aa. Under a high salt dietary regimen, both systolic and diastolic BP of Resp18 mutant rats were significantly increased compared to SS rats (151±3 vs.170±6mmHg; 116±2vs.129±4mmHg n=10-12, p &lt;0.05). Resp18 mutant rats demonstrated higher proteinuria compared to SS rats (221±14vs.268±14mg of protein/kg body weight/24hr; n=14-25, p &lt;0.05). In vascular reactivity experiment, Resp18 mutant rat mesenteric arteries demonstrated significantly reduced relaxation as compared to SS rats (n=4, p &lt;0.05). An associated decrease in sodium excretion and an increase in glucose excretion were also observed in urine samples of Resp18 mutant rats compared to SS rats (51±7.3vs.27±2.7meq/L/24hr; 10±0.3 vs. 14±1.4mg/dl/24hr,n=5-8, p &lt;0.05).Renal histology examination revealed that Resp18 mutant rat kidneys showed increased fibrosis compared to SS rats. The median survival of Resp18 mutant rats was 259 days, which was significantly lower than the median survival of 309 days for the SS (n=8-16, p &lt;0.05). In conclusion, the data suggest that Resp18 is a gene associated with the development of hypertension, renal disease and increased mortality in the SS rats. Resp18 is a molecule involved in the secretory pathway and thereby, future studies will be conducted to examine the mechanistic links between Resp18 , its function in the secretory pathway and BP regulation.

Abstract 070: Discovery of a Novel Class of Endogenous, Small-molecule, Potent, Efficacious and Potassium-sparing Diuretics/Natriuretics with Antihypertensive and Glucosuric Activity

In vivo, guanine moieties in DNA, RNA, guanine nucleotides or guanosine can undergo nitration (e.g., by peroxynitrite) or hydroxylation (e.g., by superoxide anion) on position 8 of the purine ring. Catabolism of these biomolecules leads to the in vivo production of a diverse group of 8-nitro, 8-amino and 8-hydroxy guanosine and guanine compounds. Since the renal effects of these compounds are entirely unknown, we examined in rats the effects of guanosine, guanine, 8-nitroguanosine, 8-nitroguanine, 8-hydroxyguanosine, 8-hydroxyguanine, 8-hydroxy-2-deoxyguanosine, 8-aminoguanosine and 8-aminoguanine (33 μmoles/kg/min; intravenous infusion for 115 minutes) on excretion of Na + , K + and glucose. Guanosine, 8-nitroguanosine and 8-hydroxy-2-deoxyguanosine had minimal activity. Guanine, 8-nitroguanine, 8-hydroxyguanosine and 8-hydroxyguanine had moderate natriuretic activity (increased sodium excretion by 9.4-fold, 7.8-fold, 7.1-fold and 8.6-fold, respectively). In contrast, 8-aminoguanosine (n=6) and 8-aminoguanine (n=6) were highly efficacious and increased Na + excretion by 26.6-fold (from 5.13 ± 2.16 to 136.44 ± 20.14 μmoles/30 min) and 17.2-fold (from 4.38 ± 2.00 to 75.28 ± 23.37 μmoles/30 min), respectively. 8-Aminoguanosine and 8-aminoguanine also increased glucose excretion by 12.1-fold (from 36.68 ± 11.22 to 445.11 ± 63.78 μg/30 min) and 12.2-fold (from 31.40 ± 16.70 to 382.68 ± 97.81 μg/30 min), respectively, and decreased K + excretion by 69.1% (from 51.11 ± 11.37 to 15.78 ± 2.74 μmoles/30 min) and 71.0% (from 28.57 ± 6.62 to 8.28 ± 2.14 μmoles/30 min), respectively. Radiotelemetry studies demonstrated that 8-aminoguanosine (n=3) and 8-aminoguanine (n=3) in drinking water (5 mg/kg/day) suppressed deoxycorticosterone/salt-induced (DOCA/salt) hypertension. For example, in untreated DOCA/salt rats, MABP increased from 103 ± 4 to 184 ± 9 mm Hg after 65 days of DOCA/salt; whereas in 8-aminoguanosine-treated DOCA/salt rats, MABP increased from 98 ± 2 to 148 ± 9 mm Hg during the same time period. We conclude that 8-aminoguanosine and 8-aminoguanine are endogenous, potent and efficacious K + -sparing diuretics/natriuretics that may regulate renal function and blood pressure and may represent a new class of antihypertensive drugs.