BACKGROUND:Atrial and brain natriuretic peptides activate GC-A/NPRA (guanylyl cyclase-A/natriuretic peptide receptor-A) and regulate blood pressure and electrolyte homeostasis. Renal tubule (RT) dysfunction results in decreased kidney function and increased blood pressure. We determined the sex-specific consequences of RT cell-specific deletion of Npr1 (encoding NPRA) on blood pressure and renal hemodynamics.METHODS:Mice were generated with inducible RT knockout by breeding lox-flanked (flox/flox: f/f) exons 1 to 2 in Npr1 with mice expressing the Pax8-rtTA-LC-1-Cre transgene. Doxycycline-treated RT cell-specific Npr1 knockout (Npr1 f/-), heterozygous (HT; Npr1 f/+), and wild-type (Npr1 f/f) male and female mice were used. Proximal tubule, distal tubule, and cortical collecting duct were isolated from RT-Npr1 knockout mice and did not express Npr1 mRNA or protein.RESULTS:RT cell-specific male knockout and HT mice showed significantly lower glomerular filtration rate, creatinine clearance, and urinary sodium excretion than female mice, compared with wild-type mice. The effect of Npr1 deletion was more severe on high-salt diets than their normal-diet counterparts. Loss of Npr1 in RT segments significantly increased systolic blood pressure and mean arterial pressure in a sex-specific manner. Mutant male mice showed higher total urinary protein and albumin-creatinine ratios than female mice. On a high-salt diet, male knockout and HT mice showed greater salt sensitivity than female mice.CONCLUSIONS:Loss of Npr1 along the nephron tubules leads to arterial hypertension and abnormal renal functional hemodynamic changes that are more pronounced in male mice compared with female mice.

Background The renal sympathetic nervous system modulates systemic blood pressure, cardiac performance, and renal function. Pathological increases in renal sympathetic nerve activity contribute to the pathogenesis of heart failure with preserved ejection fraction (HFpEF). We investigated the effects of renal sympathetic denervation performed at early or late stages of HFpEF progression. Methods and Results Male ZSF1 obese rats were subjected to radiofrequency renal denervation (RF‐RDN) or sham procedure at either 8 weeks or 20 weeks of age and assessed for cardiovascular function, exercise capacity, and cardiorenal fibrosis. Renal norepinephrine and renal nerve tyrosine hydroxylase staining were performed to quantify denervation following RF‐RDN. In addition, renal injury, oxidative stress, inflammation, and profibrotic biomarkers were evaluated to determine pathways associated with RDN. RF‐RDN significantly reduced renal norepinephrine and tyrosine hydroxylase content in both study cohorts. RF‐RDN therapy performed at 8 weeks of age attenuated cardiac dysfunction, reduced cardiorenal fibrosis, and improved endothelial‐dependent vascular reactivity. These improvements were associated with reductions in renal injury markers, expression of renal NLR family pyrin domain containing 3/interleukin 1β, and expression of profibrotic mediators. RF‐RDN failed to exert beneficial effects when administered in the 20‐week‐old HFpEF cohort. Conclusions Our data demonstrate that early RF‐RDN therapy protects against HFpEF disease progression in part due to the attenuation of renal fibrosis and inflammation. In contrast, the renoprotective and left ventricular functional improvements were lost when RF‐RDN was performed in later HFpEF progression. These results suggest that RDN may be a viable treatment option for HFpEF during the early stages of this systemic inflammatory disease.

Atrial and brain natriuretic peptides (ANP and BNP) bind to guanylyl cyclase A/natriuretic peptide receptor A (GC-A/NPRA), stimulating natriuresis and diuresis and reducing blood pressure (BP), but the role of ANP/NPRA signaling in podocytes (highly specialized epithelial cells covering the outer surfaces of renal glomerular capillaries) remains unclear. This study aimed to determine the effect of conditional deletion of podocyte-specific Npr1 (encoding NPRA) gene knockout (KO) in male and female mice. Tamoxifen-treated wild-type control (PD Npr1 f/f; WT), heterozygous (PD-Cre-Npr1 f/+; HT), and KO (PD-Cre-Npr1 f/-) mice were fed a normal-, low-, or high-salt diet for 4 wk. Podocytes isolated from HT and KO male and female mice showed complete absence of Npr1 mRNA and NPRA protein compared with WT mice. BP, plasma creatinine, plasma sodium, urinary protein, and albumin/creatinine ratio were significantly increased, whereas plasma total protein, albumin, creatinine clearance, and urinary sodium levels were significantly reduced in the HT and KO male and female mice compared with WT mice. These changes were significantly greater in males than in females. On a normal-salt diet, glomerular filtration rate was significantly decreased in PD Npr1 HT and KO male and female mice compared with WT mice. Immunofluorescence of podocin and synaptopodin was also significantly reduced in HT and KO mice compared with WT mice. These observations suggest that in podocytes, ANP/NPRA signaling may be crucial in the maintenance and regulation of glomerular filtration and BP and serve as a biomarker of renal function in a sex-dependent manner.NEW & NOTEWORTHY Our results demonstrate that the podocyte-specific deletion of Npr1 showed increased blood pressure (BP) and altered biomarkers of renal functions, with greater magnitudes in animals fed a high-salt diet in a sex-dependent manner. The results suggest a direct and sex-dependent effect of Npr1 ablation in podocytes on the regulation of BP and renal function and reveal that podocytes may be considered an important target for the ANP-BNP/NPRA/cGMP signaling cascade.

PURPOSE: Diuretic resistance is a failure to achieve a therapeutically desired increase in the renal excretion of sodium and water and reduction in edema despite a full dose of a loop diuretic. High levels of antidiuretic hormone (ADH) have been associated with reduced urine output in heart failure patients. However, ADH’s contribution to the development of diuretic resistance is not known. Assuming that ADH may be released in response to the diuresis produced by loop diuretics, we tested the premise that co-treatment of rats with nalfurafine, a centrally acting kappa opioid (KOR) agonist that inhibits the release of ADH would prevent and/or reverse diuretic resistance to the loop diuretic furosemide. METHODS: Changes in 5-hr urine output (metabolic cages; no water access during collection), urinary Na/K excretion, and osmolality were measured in male Sprague-Dawley rats administered twice-daily i.p. injections (9:00am, 2:00pm; n=6/group) for 11 days with 1) furosemide only (F, 10mg/kg, i.p.; days 1-11), 2) furosemide + nalfurafine (F+N, 10ug/kg, i.p.; days 1-11) or 3) F (days 1-5) followed by F+N (days 6-11). 5-hr urine collection was measured in between the morning and afternoon drug injections and rats were returned to home cages. Control 5-hr urine samples (saline, i.p.) were collected 2 days prior to beginning drug treatments. SUMMARY: Initial treatment (day 1) of rats with F alone and F+N markedly increased urine output. However, over days 6-10, urine output was significantly reduced (diuretic resistance) in rats that continued to receive F alone. Daily co-treatment of F+N beginning day 1 maintained a marked 5-hrdiuresis for all 11 days. Further, delaying addition of nalfurafine co-administration with F until day 6 reversed established diuretic resistance as noted by a marked increase in diuresis over days 6-10 with F+N cotreatment. Initial treatment (day 1) of rats with furosemide also produced a marked natriuresis and kaliuresis. However, on subsequent days (2-11) there was a significant decrease in the renal excretion of sodium and potassium that remained lower in all 3 treatment groups. In contrast, nalfurafine co-treatment beginning either day 1 (Group 2) or day 6 (Group 3) increased free-water clearance as compared to furosemide alone (Group 1). CONCLUSIONS: These results demonstrate that co-administration of the KOR agonist nalfurafine prevented and reversed diuretic resistance to furosemide without worsening electrolyte excretion. Further, these findings support the premise that in response to fluid loss caused by repeated loop diuretic administration, a compensatory release and renal action of ADH plays an important role in mediating loop diuretic resistance. NIH P30GM106392 (DK) LSUHSC REP243 (DK). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

We determined the epigenetic mechanisms regulating mean arterial pressure (MAP) and renal dysfunction in guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA) gene-targeted mice. The Npr1 (encoding NPRA) gene-targeted mice were treated with class 1 specific histone deacetylase inhibitor (HDACi) mocetinostat (MGCD) to determine the epigenetic changes in a sex-specific manner. Adult male and female Npr1 haplotype (1-copy; Npr1+/-), wild-type (2-copy; Npr1+/+), and gene-duplicated heterozygous (3-copy; Npr1++/+) mice were intraperitoneally injected with MGCD (2 mg/kg) for 14 days. BP, renal function, histopathology, and epigenetic changes were measured. One-copy male mice showed significantly increased MAP, renal dysfunction, and fibrosis than 2-copy and 3-copy mice. Furthermore, HDAC1/2, collagen1alpha-2 (Col1α-2), and alpha smooth muscle actin (α-SMA) were significantly increased in 1-copy mice compared with 2-copy controls. The expression of antifibrotic microRNA-133a was attenuated in 1-copy mice but to a greater extent in males than females. NF-κB was localized at significantly lower levels in cytoplasm than in the nucleus with stronger DNA binding activity in 1-copy mice. MGCD significantly lowered BP, improved creatinine clearance, and repaired renal histopathology. The inhibition of class I HDACs led to a sex-dependent distinctive stimulation of acetylated positive histone marks and inhibition of methylated repressive histone marks in Npr1 1-copy mice; however, it epigenetically lowered MAP, repaired renal fibrosis, and proteinuria and suppressed NF-kB differentially in males versus females. Our results suggest a role for epigenetic targets affecting hypertension and renal dysfunction in a sex-specific manner.

Anderson, Ashlyn Y.; Gao, Juan; Johnson, Kara; Denys, Ian B.; Beckendorf, Luke E.; Meariman, Jacob K.; Kapusta, Daniel R. Author Information

OBJECTIVES/GOALS: SGLT2i therapy is currently a cornerstone in heart failure with preserved ejection fraction (HFpEF) therapy. Similarly, H2S has been shown to be beneficial in preclinical models of heart failure. With this in mind, we sought to investigate the effects of the SGLT2i and H2S donor therapy alone or in combination in a rodent model of cardiometabolic HFpEF. METHODS/STUDY POPULATION: Male C57BL/6N mice (9 weeks of age) were fed a high fat, Western diet (HFD) and received L-NG-Nitro arginine methyl ester (L-NAME) in the drinking water (0.5 g/L) to induce HFpEF. At 5 weeks, animals were randomized to either control, H2S donor (SG-1002, 90 mg/kg/d, P.O), Empagliflozin (155 mg/L, P.O), or the combination of SG-1002 and Empagliflozin for an additional 5 weeks while being maintained on HFD and L-NAME. Echocardiography, left ventricular invasive LV and systemic hemodynamics, and exercise capacity testing were performed to assess cardiovascular disease severity. Fasted glucose, circulating triglyceride and cholesterol content were similarly measured to quantify key clinical metabolic parameters. H2S and its metabolite, sulfane sulfur, were quantified to assure adequate H2S donation. RESULTS/ANTICIPATED RESULTS: Administration of SG-1002 restored H2S and sulfane sulfur to normal circulating levels. All treatment groups exhibited similar improvements in LV diastolic dysfunction as measured by E/E’and LVEDP. Combination therapy significantly improved exercise capacity whereas the monotherapy groups did not. Treatment with SG-1002 decreased fasting glucose and circulating cholesterol while all treatment groups displayed decreased circulating triglycerides and body weight compared to HFpEF control. DISCUSSION/SIGNIFICANCE: These data indicate that restoring H2S or treatment with an SGLT2i in this preclinical HFpEF model attenuates pathology. Combination of both drugs exhibited greater benefit than either monotherapy in important HFpEF parameters such as exercise capacity. Further studies are underway to characterize the benefits observed from combination therapy.

Nalfurafine is a G-protein-biased KOR (kappa opioid receptor) agonist that produces analgesia and lacks central nervous system adverse effects. Here, we examined the cardiovascular and renal responses to intravenous and oral nalfurafine alone and in combination with furosemide, hydrochlorothiazide, or amiloride. We hypothesized that nalfurafine, given its distinct mechanism of vasopressin inhibition, would increase urine output to these diuretics and limit electrolyte loss. Following catheterization, conscious Sprague-Dawley rats received an isotonic saline infusion and were then administered an intravenous bolus of nalfurafine, a diuretic, or a combination. Mean arterial pressure, heart rate, and urine output were recorded for 90 minutes. In another study, rats were placed in metabolic cages and administered drug in an oral volume load. Hourly urine samples were then collected for 5 hours. Intravenous and oral nalfurafine produced a marked diuresis, antinatriuresis, antikaliuresis, and a decrease in mean arterial pressure. Compared with diuretic treatment alone, intravenous coadministration with nalfurafine significantly increased urine output to furosemide and hydrochlorothiazide and decreased sodium and potassium excretion. Notably, mean arterial pressure was reduced with nalfurafine/diuretic combination therapy compared to diuretics alone. Similarly, oral coadministration of nalfurafine significantly increased urine output to hydrochlorothiazide and decreased sodium and potassium excretion, whereas combination with furosemide only limited the amount of sodium excreted. Further, both intravenous and oral coadministration of nalfurafine enhanced the diuresis to amiloride and decreased sodium excretion. Together, these findings demonstrate that nalfurafine enhances the diuresis to standard-of-care diuretics without causing an excessive loss of electrolytes, offering a new approach to treat several cardiovascular conditions.

Background and Purpose Partial agonists of the nociceptin opioid peptide (NOP) receptor have potential therapeutic use as antihypertensive and water diuretics (aquaretics). To date, peptide NOP receptor ligands have failed to progress in clinical trials due to poor pharmacokinetics and adverse effects. Nonpeptide, small-molecule NOP receptor ligands may be more suitable as therapeutic agents. This study investigated the cardiovascular and renal responses produced by the novel nonpeptide NOP agonists AT-403, AT-090, AT-127, and AT-039. Experimental Approach Changes in mean arterial pressure (MAP), heart rate (HR), renal excretory function and occurrence of sedation and hyperphagia were determined before and after i.v. bolus injection or infusion of the NOP agonists in conscious Sprague-Dawley rats. Additional studies involving (i) measurement of renal sympathetic nerve activity (RSNA) and (ii) renal denervation were conducted to investigate the role of the renal nerves in the cardiorenal responses to AT-039. Key Results Bolus i.v. injection of AT-403, AT-090, AT-127 and AT-039 produced significant decreases in MAP and HR and a sodium-sparing diuresis. AT-403, AT-090, and AT-127, but not AT-039, induced sedation and hyperphagia at all doses tested. Infusion i.v. of AT-039 produced hypotension and aquaresis without adverse central nervous system effects or change in HR, responses that were also observed in renal denervated rats. Conclusions and Implications Nonpeptide NOP agonists decrease blood pressure and produce aquaresis in conscious rodents. Due to lack of sedation and hyperphagia, AT-039 represents a novel NOP agonist that may be useful for treatment of hypertension and/or volume overload/hyponatraemic states.

Difelikefalin is a peripherally restricted kappa opioid receptor (KOR) agonist that was recently approved by the FDA to treat pruritis in dialysis patients. Here, we investigated the cardiovascular and renal responses to difelikefalin, and using the KOR antagonist norbinaltorphimine (norBNI), examined whether any difelikefalin-induced changes in the renal excretion of water and/or electrolytes were mediated through a central or peripheral KOR pathway. The effects of norBNI pretreatment on nalfurafine, a KOR agonist that crosses the blood-brain barrier, were also examined. We hypothesized that difelikefalin would alter urine output differently than nalfurafine, given that KOR agonists produce diuresis via activating central KORs to inhibit vasopressin release. Following catheterization, conscious Sprague-Dawley rats were infused i.v. with isotonic saline and pretreated with norBNI centrally via an intracerebroventricular (ICV) cannula or peripherally via an intravenous catheter. After stabilization, difelikefalin or nalfurafine was administered i.v. and urine output, heart rate and mean arterial pressure (MAP) were recorded for 90 min. Difelikefalin produced a significant increase in urine output, and significant decrease in urinary sodium and potassium excretion, urine osmolality, and MAP. ICV norBNI pretreatment markedly attenuated the increase in urine output caused by difelikefalin and nalfurafine but did not inhibit the electrolyte effects. However, IV norBNI pretreatment prevented all responses to difelikefalin and nalfurafine. Together, these findings demonstrate that difelikefalin and nalfurafine utilize central KOR pathways to elicit diuresis and a decrease in MAP but enhance renal tubular electrolyte reabsorption through a peripheral KOR pathway, providing important insight into two clinically useful KOR agonists.

The adverse effects of mu opioid agonists have spurred a renewed interest in using kappa opioid receptor (KOR) agonists as analgesics. KOR agonists also have potential for development as diuretics for the treatment of edema and hypertension. Here, we evaluated the discriminative stimulus, antinociceptive, and diuretic effects of the kappa agonist (±)-trans-U-50488 and its stereoisomers (-)-(1S,2S)-U-50488 or (+)-(1R,2R)-U-50488) alone and in combination with the cannabinoid agonist (-)-CP 55,940. To establish (±)-U-50488 as a discriminative stimulus, rats (n = 12) were trained to discriminate intraperitoneal (i.p.) administration of 5.6 mg/kg of (±)-trans-U-50488 from saline under a fixed-ratio 20 (FR-20) schedule of food reinforcement. Then, antinociception was assessed using two procedures: warm water tail withdrawal and von Frey paw withdrawal. Diuretic effects were assessed in separate rats (n = 6/group). Doses of (±)-U-50488 and (-)-U-50488 that served as discriminative stimuli produced significant increases in urine output, but at lower doses than those that produced antinociception. In contrast, (+)-U-50488 alone had no discriminative stimulus or diuretic effects at the doses tested, but did produce antinociception in the von Frey assay. When three cannabinoids and morphine were tested in the (±)-U-50488 discrimination procedure to determine the similarity of these drugs' discriminative stimulus effects to those for (±)-U-50488, the rank order similarity was (-)-CP 55,940 > (-)-trans-THC > (+)-WIN 55,212-2 ≥ morphine. (-)-CP 55,940 alone (0.056 mg/kg) partially substituted for the discriminative stimulus effects of (±)-U-50488 and produced significant diuretic and antinociceptive effects. (-)-CP 55,940 in combination with (±)-U-50488 also produced a two-fold leftward shift in the discriminative stimulus curve for (±)-U-50488, and near-additive antinociception with (±)-U-50488 and (+)-U-50488. Further, the diuretic effect of (-)-CP 55,940 was enhanced by a dose of (+)-U50488, which itself did not alter urine output. These data together indicate that a combination of cannabinoid and kappa opioid agonists can enhance diuresis, but may have limited potential for serving as opioid-sparing pharmacotherapeutics for treatment of pain.

Mice lacking Npr1 (encoding guanylyl cyclase/natriuretic peptide receptor‐A; GC‐A/NPRA) exhibit hypertension, kidney disease, and heart failure; however, the epigenetic determinants regulating Npr1 expression and renal function are not well understood. The objective of this study was to investigate the effect of class I‐specific histone deacetylase (HDAC) inhibitor, mocetinostat (MGCD0103; MGCD) on NPRA expression and regulation of mean arterial pressure (MAP) and renal pathology. Adult male and female Npr1 haplotype (1‐copy, Npr1+/‐), wild‐type (2‐copy, Npr1+/+), and gene‐duplicated (3‐copy, Npr1++/+) mice were injected intraperitoneally with MGCD (2 mg/kg) at alternate days for 2‐weeks. Treatment with MGCD significantly enhanced NPRA protein levels and GC activity in male and female mice in all three genotypes. MAP was monitored by telemetry recording. Sex‐differences were observed in MAP as female mice had lower MAP (p < 0.01) than male mice, in all genotypes; whereas, 1‐copy mice exhibited higher MAP than 2‐copy mice. Treatments with MGCD distinctly reduced MAP in 1‐copy and 2‐copy male mice (untreated 1‐copy, 125 ± 3 vs. treated 1‐copy, 108 ± 3 mmHg; p < 0.001; untreated 2‐copy, 98 ± 2 vs. treated 2‐copy, 90 ± 2 mmHg; p < 0.01) and 1‐copy and 2‐copy female mice (untreated 1‐copy, 117 ± 3 vs. treated 1‐copy, 105 ± 2 mmHg; p < 0.001; untreated 2‐copy, 90 ± 2 vs. treated 2‐copy, 84 ± 2 mmHg; p < 0.01). Treatment with MGCD attenuated HDAC activity by 30% in male and 40% in female animals (p < 0.05). The Western blot analyses indicated that 1‐copy male and female mice showed upregulation of alpha‐smooth muscle actin (α‐SMA; 39% and 29%, p < 0.05) and collagen 1 alpha 2 (COL1α2; 49% and 20%, p < 0.05) proteins, respectively, compared with 2‐copy mice. Picrosirius red staining in renal sections showed significant collagen deposition in 1‐copy mice compared with 2‐copy animals of both sexes. MGCD reduced fibrosis by 30%‐45% (p < 0.05) in treated 1‐copy mice compared with untreated control mice in both sexes. The present results indicate that MGCD lowers MAP, and repairs renal fibrosis in male and female mice. These findings will have important implications for treatment of hypertension and renal injury in humans in both genders.

Kappa opioid receptor (KOR) agonists produce a variety of beneficial effects, including a water diuresis, but their translation into the clinic has been hindered by psychotomimetic adverse effects. Nalfurafine is a novel, G protein biased KOR agonist that has been shown to produce several desired effects of KOR agonists, while avoiding central adverse effects. To more fully explore the clinical potential of this drug, this study examined the cardiovascular and renal responses to i.v. nalfurafine alone or in combination with the clinically used diuretics: furosemide, hydrochlorothiazide (HCTZ), and amiloride. Following chronic instrumentation, conscious Sprague-Dawley rats were continuously infused i.v. with isotonic saline; after stabilization, rats were administered i.v. bolus nalfurafine, diuretics, diuretics combined with nalfurafine, or vehicle, and mean arterial pressure (MAP), heart rate (HR), and urine output were recorded for 90 min. IV nalfurafine produced a marked diuresis, antinatriuresis, antikaliuresis, and decrease in MAP without eliciting a change in HR. As compared to diuretic treatment alone, co-administration of nalfurafine notably increased the total urine output to furosemide and HCTZ while reducing the amount of sodium and potassium excreted. When combined with amiloride, nalfurafine also increased the diuresis and decreased the amount of sodium excreted. In contrast to these diuretics administered alone, MAP was reduced with nalfurafine combination therapy. Together, these findings demonstrate that nalfurafine has a clinically important action to augment the diuresis to classical diuretics without causing excessive loss of electrolytes characteristic of these drugs. Combination therapy of nalfurafine with loop/thiazide diuretics may offer a new approach to treat several cardiovascular conditions such as hypertension, volume overloaded states, and electrolyte abnormalities.

Nalfurafine, a G protein-biased kappa opioid receptor (KOR) agonist that produces analgesia and is devoid of CNS adverse effects, is used in Japan to treat pruritis in dialysis patients. Our lab has shown that in rats, IV nalfurafine produces a marked diuresis, antinatriuresis, antikaliuresis, and decrease in blood pressure. Here, we examined the cardiovascular and renal responses to IV and oral nalfurafine in combination with furosemide or hydrochlorothiazide (HCTZ). We hypothesized that combining nalfurafine with these diuretics would increase urine output, given its distinct mechanism of vasopressin inhibition, and limit electrolyte loss. Following chronic catheterization, conscious Sprague-Dawley rats received an isotonic saline infusion, and after stabilization, were administered an IV bolus diuretic alone or in combination with nalfurafine. Mean arterial pressure (MAP), heart rate (HR), and urine output were recorded for 90-min. In a separate study, rats were placed in metabolic cages, and following 2-hour acclimation, were administered drug in a volume load (20 cc/kg) via oral gavage. Hourly urine samples were then collected for five hours. When compared to diuretic treatment alone, IV co-administration with nalfurafine significantly increased total urine output to furosemide and HCTZ while reducing the amount of sodium and potassium excreted (Table 1). Notably, MAP was reduced with nalfurafine/diuretic combination therapy compared to diuretics alone. Similarly, oral co-administration of nalfurafine significantly increased the urine output to HCTZ and reduced the amount of sodium and potassium excreted, whereas combination with furosemide only limited the amount of sodium excreted (Table 1). Together, these findings demonstrate that nalfurafine enhances the diuresis to standard-of-care diuretics without causing an excessive loss of electrolytes, which may offer a new approach to treat several cardiovascular conditions.

Heart Failure with Preserved Ejection Fraction (HFpEF) is a complex heterogeneous disease that currently affects approximately 3 million in the US and accounts for 60% of all heart failure hospitalizations. HFpEF is associated with significant morbidity, mortality and healthcare expenditures. At present, there are no FDA approved therapies for reducing mortality and hospitalization in HFpEF patients. The lack of approved therapies is due in part to a lack of preclinical models that faithfully mimic the clinical presentation of HFpEF.The obese ZSF‐1 rat is genetically predisposed to the development of hypertension, obesity, dyslipidemia, and diabetes, all of which contribute to the pathogenesis of HFpEF. We investigated the suitability of the obese ZSF‐1 rat as a model of HFpEF. Both obese and lean control ZSF‐1 rats (n = 4–6 per group) were utilized for these studies. The rats were studied from 16 weeks to 24 weeks of age. We measured several clinical parameters including cardiac structure and function (2‐D echocardiography), left ventricular (LV) pressures (LV Millar catheter), cardiac fibrosis, conscious blood pressure and heart rate (DSI radiotelemeters), vascular function, exercise capacity (rodent treadmill), and serum lipid and triglyceride levels (standard blood ELISA assays).Obese ZSF‐1 rats exhibited a significant increase in body weight and systemic blood pressure combined with hyperglycemia and insulin insensitivity. Echocardiographic evaluation of the left ventricle (LV) revealed highly significant increases in both the E/A and E/E′ ratios. LV end‐diastolic pressure (LVEDP) and LV relaxation (Tau) were decreased in the obese ZSF‐1 rats. Histological evaluation of the hearts revealed significant increases in cardiac fibrosis and cardiac myocyte injury in the obese vs. lean ZSF‐1. Furthermore, vascular reactivity and circulating nitric oxide levels were reduced in the obese ZSF‐1 rats. Exercise capacity testing revealed that exercise capacity was very significantly reduced in the ZSF‐1 obese rat throughout the 8 week experimental protocol. All these findings are consistent with the HFpEF phenotype observed in human HFpEF patients.This preclinical model of HFpEF, will provide novel insights into the pathobiology of HFpEF and provide a critically important platform for testing HFpEF therapeutics. Our future studies will be aimed at the identification of novel therapeutic interventions to treat HFpEF.Support or Funding InformationNational Institutes of General Medical Sciences (NIGMS) COBRE grant no. P30GM106392 to Dr. KapustaFigure 1

Background: Heart failure with preserved ejection fraction (HFpEF) has emerged as a subclass of heart failure for which there are no effective treatments. HFpEF is induced in a large number of patients by central obesity, metabolic syndrome, and sustained activation of the sympathetic nervous system (SNS). Methods: We examined the effects of RDN in a clinically relevant model of HFpEF. The ZSF1-Obese rat exhibits the key components of cardiometabolic HFpEF including hypertension and diabetes. At 20 wks of age, ZSF1-Obese rats underwent bilateral radiofrequency RDN (RF-RDN) or sham RF-RDN and were followed for 6 weeks. LV function, blood pressure, LVEDP, vascular function, myocardial fibrosis, metabolic profiling, and exercise capacity were evaluated. We also assessed mitochondrial function of cardiac and skeletal muscle. Results: RF-RDN resulted in significant improvements in LV diastolic function, vascular relaxation, and exercise capacity. Significant reductions in blood pressure and LVEDP were observed following RF-RDN treatment. RF-RDN ameliorated cardiac fibrosis while improving cardiac and skeletal muscle mitochondrial function. We did not observe any effects of RF-RDN on the metabolic status of the ZSF-1 rat. Conclusion: Our data suggest that RF-RDN is a viable treatment option for cardiometabolic HFpEF through halting renal SNS hyperactivation and enhancing mitochondrial function to exert beneficial effects on the heart and circulation.