Cinaciguat prevents the development of pathologic hypertrophy in a rat model of left ventricular pressure overload

Role of the NO-GC/cGMP signaling pathway in platelet biomechanics

Cyclic guanosine monophosphate (cGMP) is a second messenger produced by the NO-sensitive guanylyl cyclase (NO-GC). The NO-GC/cGMP pathway in platelets has been extensively studied. However, its role in regulating the biomechanical properties of platelets has not yet been addressed and remains unknown. We therefore investigated the stiffness of living platelets after treatment with the NO-GC stimulator riociguat or the NO-GC activator cinaciguat using scanning ion conductance microscopy (SICM). Stimulation of human and murine platelets with cGMP-modulating drugs decreased cellular stiffness and downregulated P-selectin, a marker for platelet activation. We also quantified changes in platelet shape using deep learning-based platelet morphometry, finding that platelets become more circular upon treatment with cGMP-modulating drugs. To test for clinical applicability of NO-GC stimulators in the context of increased thrombogenicity risk, we investigated the effect of riociguat on platelets from human immunodeficiency virus (HIV)-positive patients taking abacavir sulfate (ABC)-containing regimens. Our results corroborate a functional role of the NO-GC/cGMP pathway in platelet biomechanics, indicating that biomechanical properties such as stiffness or shape could be used as novel biomarkers in clinical research.

Pressure overload-induced systolic heart failure is associated with characteristic myocardial microRNA expression signature and post-transcriptional gene regulation in male rats

Although systolic function characteristically shows gradual impairment in pressure overload (PO)-evoked left ventricular (LV) hypertrophy (LVH), rapid progression to congestive heart failure (HF) occurs in distinct cases. The molecular mechanisms for the differences in maladaptation are unknown. Here, we examined microRNA (miRNA) expression and miRNA-driven posttranscriptional gene regulation in the two forms of PO-induced LVH (with/without systolic HF). PO was induced by aortic banding (AB) in male Sprague-Dawley rats. Sham-operated animals were controls. The majority of AB animals demonstrated concentric LVH and slightly decreased systolic function (termed as ABLVH). In contrast, in some AB rats severely reduced ejection fraction, LV dilatation and increased lung weight-to-tibial length ratio was noted (referred to as ABHF). Global LV miRNA sequencing revealed fifty differentially regulated miRNAs in ABHF compared to ABLVH. Network theoretical miRNA-target analysis predicted more than three thousand genes with miRNA-driven dysregulation between the two groups. Seventeen genes with high node strength value were selected for target validation, of which five (Fmr1, Zfpm2, Wasl, Ets1, Atg16l1) showed decreased mRNA expression in ABHF by PCR. PO-evoked systolic HF is associated with unique miRNA alterations, which negatively regulate the mRNA expression of Fmr1, Zfmp2, Wasl, Ets1 and Atg16l1.

Novel application potential of cinaciguat in the treatment of mixed hyperlipidemia through targeting PTL/NPC1L1 and alleviating intestinal microbiota dysbiosis and metabolic disorders

Mixed hyperlipidemia, characterized by high levels of triglycerides and cholesterol, is a key risk factor leading to atherosclerosis and other cardiovascular diseases. Existing clinical drugs usually only work on a single indicator, decreasing either triglyceride or cholesterol levels. Developing dual-acting agents that reduce both triglycerides and cholesterol remains a great challenge. Pancreatic triglyceride lipase (PTL) and Niemann-Pick C1-like 1 (NPC1L1) have been identified as crucial proteins in the transport of triglycerides and cholesterol. Here, cinaciguat, a known agent used in the treatment of acute decompensated heart failure, was identified as a potent dual inhibitor targeting PTL and NPC1L1. We presented in vitro evidence from surface plasmon resonance analysis that cinaciguat interacted with PTL and NPC1L1. Furthermore, cinaciguat exhibited potent PTL-inhibition activity. Fluorescence-labeled cholesterol uptake analysis and confocal imaging showed that cinaciguat effectively inhibited cholesterol uptake. In vivo evaluation showed that cinaciguat significantly reduced the plasma levels of triglycerides and cholesterol, and effectively alleviated high-fat diet-induced intestinal microbiota dysbiosis and metabolic disorders. These results collectively suggest that cinaciguat has the potential to be further developed for the therapy of mixed hyperlipidemia.

CYB5R3 in type II alveolar epithelial cells protects against lung fibrosis by suppressing TGF-β1 signaling

Type II alveolar epithelial cell (AECII) redox imbalance contributes to the pathogenesis of idiopathic pulmonary fibrosis (IPF), a deadly disease with limited treatment options. Here, we show that expression of membrane-bound cytochrome B5 reductase 3 (CYB5R3), an enzyme critical for maintaining cellular redox homeostasis and soluble guanylate cyclase (sGC) heme iron redox state, is diminished in IPF AECIIs. Deficiency of CYB5R3 in AECIIs led to sustained activation of the pro-fibrotic factor TGF-β1 and increased susceptibility to lung fibrosis. We further show that CYB5R3 is a critical regulator of ERK1/2 phosphorylation and the sGC/cGMP/protein kinase G axis that modulates activation of the TGF-β1 signaling pathway. We demonstrate that sGC agonists (BAY 41-8543 and BAY 54-6544) are effective in reducing the pulmonary fibrotic outcomes of in vivo deficiency of CYB5R3 in AECIIs. Taken together, these results show that CYB5R3 in AECIIs is required to maintain resilience after lung injury and fibrosis and that therapeutic manipulation of the sGC redox state could provide a basis for treating fibrotic conditions in the lung and beyond.

Shunxin decoction improves diastolic function in rats with heart failure with preserved ejection fraction induced by abdominal aorta constriction through cyclic guanosine monophosphate-dependent protein kinase Signaling Pathway

OBJECTIVE

To determine whether Shunxin decoction improves diastolic function in rats with heart failure with preserved ejection fraction (HFpEF) by regulating the cyclic guanosine monophosphate-dependent protein kinase (cGMP-PKG) signaling pathway.

METHODS

Except for control group 8 and sham surgery group 8, the remaining 32 male Sprague-Dawlay rats were developed into HFpEF rat models using the abdominal aorta constriction method. These rats in the HFpEF model were randomly divided into the model group, the Shunxin high-dose group, the Shunxin low-dose group, and the Qiliqiangxin capsule group. The three groups received high-dose Shunxin decoction, low-dose Shunxin decoction, and Qiliqiangxin capsule by gavage, respectively, for 14 d. After the intervention, the diastolic function of each rat was evaluated by testing E/A, heart index, hematoxylin-eosin staining, Masson, myocardial ultrastructure, and N-terminal pro-brain natriuretic peptide (NT-proBNP). The Bioinformatics Analysis Tool for Molecular Mechanism of Traditional Chinese Medicine (BATMAN-TCM) software was used to predict targets for which Shunxin decoction acts on the cGMP-PKG pathway. Natriuretic peptide receptor A (NPRA) and guanylate cyclase (GC) were detected by immunohistochemistry, and eNOS, phosphodiesterase 5A (PDE5A), and cGMP-dependent protein kinase 1(PKG I) were determined by Western blotting.

RESULTS

Compared to the model group, the thickness of the interventricular septum at the end of diastole (IVSd) and the thickness of the posterior wall at the end of diastole (PWd) of the Shunxin decoction high-dose group, Shunxin decoction low-dose group, and Qiliqiangxin capsule group were all significantly reduced ( < 0.01). Furthermore, Shunxin decoction high-dose group E/A value was decreased ( < 0.01). Compared to the model group, the expression of NPRA and GC increased in the Shunxin decoction low-dose group and the Qiliqiangxin capsule group ( < 0.01). Compared to the model group, the expressions of eNOS and PKG I increased ( < 0.05) in the Shunxin decoction high-dose group. The expression of PDE5A expression decreased in the myocardium of the Shunxin decoction high-dose group, Shunxin decoction low-dose group, and Qiliqiangxin capsule group compared to the model group ( < 0.01).

CONCLUSIONS

Shunxin decoction can improve diastolic function in rats with HFpEF. It increases the expression of NPRA, GC, and eNOS in the myocardial cell cGMP-PKG signaling pathway, upregulates cGMP expression, decreases PDE5A expression to reduce the cGMP degradation. Thus, the cGMP continually stimulates PKG I, reversing myocardial hypertrophy and improving myocardial compliance in HFpEF rats.

Cinaciguat (BAY-582667) Modifies Cardiopulmonary and Systemic Circulation in Chronically Hypoxic and Pulmonary Hypertensive Neonatal Lambs in the Alto Andino

Neonatal pulmonary hypertension (NPHT) is produced by sustained pulmonary vasoconstriction and increased vascular remodeling. Soluble guanylyl cyclase (sGC) participates in signaling pathways that induce vascular vasodilation and reduce vascular remodeling. However, when sGC is oxidized and/or loses its heme group, it does not respond to nitric oxide (NO), losing its vasodilating effects. sGC protein expression and function is reduced in hypertensive neonatal lambs. Currently, NPHT is treated with NO inhalation therapy; however, new treatments are needed for improved outcomes. We used Cinaciguat (BAY-582667), which activates oxidized and/or without heme group sGC in pulmonary hypertensive lambs studied at 3,600 m. Our study included 6 Cinaciguat-treated (35 ug kg−1 day−1x 7 days) and 6 Control neonates. We measured acute and chronic basal cardiovascular variables in pulmonary and systemic circulation, cardiovascular variables during a superimposed episode of acute hypoxia, remodeling of pulmonary arteries and changes in the right ventricle weight, vasoactive functions in small pulmonary arteries, and expression of NO-sGC-cGMP signaling pathway proteins involved in vasodilation. We observed a decrease in pulmonary arterial pressure and vascular resistance during the acute treatment. In contrast, the pulmonary pressure did not change in the chronic study due to increased cardiac output, resulting in lower pulmonary vascular resistance in the last 2 days of chronic study. The latter may have had a role in decreasing right ventricular hypertrophy, although the direct effect of Cinaciguat on the heart should also be considered. During acute hypoxia, the pulmonary vascular resistance remained low compared to the Control lambs. We observed a higher lung artery density, accompanied by reduced smooth muscle and adventitia layers in the pulmonary arteries. Additionally, vasodilator function was increased, and vasoconstrictor function was decreased, with modifications in the expression of proteins linked to pulmonary vasodilation, consistent with low pulmonary vascular resistance. In summary, Cinaciguat, an activator of sGC, induces cardiopulmonary modifications in chronically hypoxic and pulmonary hypertensive newborn lambs. Therefore, Cinaciguat is a potential therapeutic tool for reducing pulmonary vascular remodeling and/or right ventricular hypertrophy in pulmonary arterial hypertension syndrome.

Myocardial work index: a marker of left ventricular contractility in pressure- or volume overload-induced heart failure

Aims

While global longitudinal strain (GLS) is considered to be a sensitive marker of left ventricular (LV) function, it is significantly influenced by loading conditions. We hypothesized that global myocardial work index (GMWI), a novel marker of LV function, may show better correlation with load‐independent markers of LV contractility in rat models of pressure‐induced or volume overload‐induced heart failure.

Methods and results

Male Wistar rats underwent either transverse aortic constriction (TAC; n = 12) or aortocaval fistula creation (ACF; n = 12), inducing LV pressure or volume overload, respectively. Sham procedures were performed to establish control groups (n = 12/12). Echocardiographic loops were obtained to determine GLS and GMWI. Pressure‐volume analysis with transient occlusion of the inferior caval vein was carried out to calculate preload recruitable stroke work (PRSW), a load‐independent ‘gold‐standard’ parameter of LV contractility. Myocardial samples were collected to assess interstitial and perivascular fibrosis area and also myocardial atrial‐type natriuretic peptide (ANP) and brain‐type natriuretic peptide (BNP) relative mRNA expression. Compared with controls, GLS was substantially lower in the TAC group (−7.0 ± 2.8 vs. −14.5 ± 2.5%; P < 0.001) and was only mildly reduced in the ACF group (−13.2 ± 2.4 vs. −15.4 ± 2.0%, P < 0.05). In contrast with these findings, PRSW and GMWI were comparable with sham in TAC (110 ± 26 vs. 116 ± 68 mmHg; 1687 ± 275 mmHg% vs. 1537 ± 662 mmHg%; both P = NS), while it was found to be significantly reduced in ACF (58 ± 14 vs. 111 ± 40 mmHg; 1328 ± 411 vs. 1934 ± 308 mmHg%, both P < 0.01). In the pooled population, GMWI (r = 0.70; P < 0.001) but not GLS (r = −0.23; P = 0.12) showed a strong correlation with PRSW. GLS correlated with interstitial (r = 0.61; P < 0.001) and perivascular fibrosis area (r = 0.54; P < 0.001), and also with myocardial ANP (r = 0.85; P < 0.001) and BNP relative mRNA expression (r = 0.75; P < 0.001), while GMWI demonstrated no or only marginal correlation with these parameters.

Conclusions

Being significantly influenced by loading conditions, GLS may not be a reliable marker of LV contractility in heart failure induced by pressure or volume overload. GMWI better reflects contractility in haemodynamic overload states, making it a more robust marker of systolic function, while GLS should be considered as an integrative marker, incorporating systolic function, haemodynamic loading state, and adverse tissue remodelling of the LV.

Stimulation of soluble guanylate cyclase improves donor organ function in rat heart transplantation

Heart transplantation remains the definitive therapy of end-stage heart failure. Ischemia-reperfusion injury occurring during transplantation is a primary determinant of long-term outcome of heart transplantation and primary graft insufficiency. Modification of the nitric oxide/soluble guanylate cyclase/cyclic guanosine monophosphate signaling pathway appears to be one of the most promising among the pharmacological interventional options. We aimed at characterizing the cardio-protective effects of the soluble guanylate cyclase stimulator riociguat in a rat model of heterotopic heart transplantation. Donor Lewis rats were treated orally with either riociguat or placebo for two days (n = 9) in each transplanted group and (n = 7) in donor groups. Following explantation, hearts were heterotopically transplanted. After one hour reperfusion, left ventricular pressure-volume relations and coronary blood flow were recorded. Molecular biological measurements and histological examination were also completed. Left ventricular contractility (systolic pressure: 117 ± 13 vs. 48 ± 5 mmHg, p < 0.001; dP/dt_max: 2963 ± 221 vs. 1653 ± 159 mmHg/s, p < 0.001), active relaxation (dP/dt_min: −2014 ± 305 vs. −1063 ± 177 mmHg/s, p = 0.02; all at 120 µl of left ventricular volume), and alteration of coronary blood flow standardized to heart weight (2.55 ± 0.32 vs. 1.67 ± 0.22 ml/min/g, p = 0.03) were markedly increased following preconditioning with riociguat. Myocardial apoptosis markers were also significantly reduced in the riociguat pretreated group as well as the antioxidant markers were elevated. Pharmacological preconditioning with riociguat decreases ischemia-reperfusion injury and improves donor organ function in our animal model of heart transplantation. Therefore, riociguat might be a potential cardioprotective agent.

Cinaciguat in combination with insulin induces a favorable effect on implant osseointegration in type 2 diabetic rats

The osseointegration process of implant is seriously impaired in type 2 diabetes mellitus (T2DM) that causes high failure rate, and insufficiency exists in current insulin therapy, creating a demand for new bone-synergistic agent. Cinaciguat, a novel type of soluble guanylate cyclase (sGC) activator, plays a vital role in glucose metabolism, inflammation control and bone regeneration. We hypothesized that the combined application of cinaciguat and insulin could reverse poor implant osseointegration in diabetes. To test this hypothesis, streptozotocin-induced diabetic rats were placed implants in the femur, and divided into five groups: control, T2DM, cinaciguat-treated T2DM (7 μg/kg), insulin-treated T2DM (12 IU/kg), cinaciguat plus insulin combination-treated T2DM (7 μg/kg and 12 IU/kg respectively), according to different treatment received. The weight and glucose levels of rats were evaluated at fixed times, and plasma level of cyclic guanosine monophosphate (cGMP) was determined before euthanasia. Three months after therapy, the femurs were isolated for pull-out test, environmental scanning electron microscope observation, microscopic computerized tomography evaluation and various histology analysis. Results revealed that diabetic rats showed the highest blood glucose level and lowest cGMP content, which led to the worst structural damage and least osseointegration. Combined treatment could attenuate the diabetes induced hyperglycemia to be normal, restore the cGMP content, protein kinase G II (PKG II) expression, phosphodiesterase-5 (PDE5) activity and ameliorate the mechanical strength, the impaired bone microarchitecture and osseointegration to the highest level. Meanwhile, monotreatment (insulin or cinaciguat) also showed restorative effect, but less. Our findings demonstrated that the cGMP/PKG II signaling pathway activated by cinaciguat mediated the favorable effects of the combined application on improving implant fixation under T2DM condition.

Myofilament Ca2+ sensitivity correlates with left ventricular contractility during the progression of pressure overload-induced left ventricular myocardial hypertrophy in rats

AIM

Here we aimed at investigating the relation between left ventricular (LV) contractility and myofilament function during the development and progression of pressure overload (PO)-induced LV myocardial hypertrophy (LVH).

METHODS

Abdominal aortic banding (AB) was performed to induce PO in rats for 6, 12 and 18 weeks. Sham operated animals served as controls. Structural and molecular alterations were investigated by serial echocardiography, histology, quantitative real-time PCR and western blot. LV function was assessed by pressure-volume analysis. Force measurement was carried out in permeabilized cardiomyocytes.

RESULTS

AB resulted in the development of pathological LVH as indicated by increased heart weight-to-tibial length ratio, LV mass index, cardiomyocyte diameter and fetal gene expression. These alterations were already present at early stage of LVH (AB-week6). Furthermore, at more advanced stages (AB-week12, AB-week18), myocardial fibrosis and chamber dilatation were also observed. From a hemodynamic point of view, the AB-wk6 group was associated with increased LV contractility, maintained ventriculo-arterial coupling (VAC) and preserved systolic function. In the same experimental group, increased myofilament Ca²⁺ sensitivity (pCa₅₀) and hyperphosphorylation of cardiac troponin-I (cTnI) at Threonine-144 was detected. In contrast, in the AB-wk12 and AB-wk18 groups, the initial augmentation of LV contractility, as well as the increased myofilament Ca²⁺ sensitivity and cTnI (Threonine-144) hyperphosphorylation diminished, leading to impaired VAC and reduced systolic performance. Strong correlation was found between LV contractility parameters and myofilament Ca²⁺-sensitivity among the study groups.

CONCLUSION

Changes in myofilament Ca²⁺ sensitivity might underlie the alterations in LV contractility during the development and progression of PO-induced LVH.

Comparison of the Reverse-Remodeling Effect of Pharmacological Soluble Guanylate Cyclase Activation With Pressure Unloading in Pathological Myocardial Left Ventricular Hypertrophy

Background: Pressure unloading induces the regression of left ventricular myocardial hypertrophy (LVH). Recent findings indicate that pharmacological activation of the soluble guanylate cyclase (sGC) – cyclic guanosine monophosphate (cGMP) pathway may also exert reverse-remodeling properties in the myocardium. Therefore, we aimed to investigate the effects of the sGC activator cinaciguat in a rat model of LVH and compare it to the “gold standard” pressure unloading therapy.

Methods: Abdominal aortic banding was performed for 6 or 12 weeks. Sham operated animals served as controls. Pressure unloading was induced by removing the aortic constriction after week 6. The animals were treated from week 7 to 12, with 10 mg/kg/day cinaciguat or with placebo p.o., respectively. Cardiac function and morphology were assessed by left ventricular pressure-volume analysis and echocardiography. Additionally, key markers of myocardial hypertrophy, fibrosis, nitro-oxidative stress, apoptosis and cGMP signaling were analyzed.

Results: Pressure unloading effectively reversed LVH, decreased collagen accumulation and provided protection against oxidative stress and apoptosis. Regression of LVH was also associated with a full recovery of cardiac function. In contrast, chronic activation of the sGC enzyme by cinaciguat at sustained pressure overload only slightly influenced pre-established hypertrophy. However, it led to increased PKG activity and had a significant impact on interstitial fibrosis, nitro-oxidative stress and apoptosis. Amelioration of the pathological structural alterations prevented the deterioration of LV systolic function (contractility and ejection fraction) and improved myocardial stiffness.

Conclusion: Our results indicate that both cinaciguat treatment and pressure unloading evoked anti-remodeling effects and improved LV function, however in a differing manners.

Selegiline reduces adiposity induced by high-fat, high-sucrose diet in male rats

BACKGROUND AND PURPOSE

Incidence and severity of obesity are increasing worldwide, however, efficient and safe pharmacological treatments are not yet available. Certain MAO inhibitors reduce body weight, although their effects on metabolic parameters have not been investigated. Here, we have assessed effects of a widely used, selective MAO-B inhibitor, selegiline, on metabolic parameters in a rat model of diet-induced obesity.

EXPERIMENTAL APPROACH

Male Long-Evans rats were given control (CON) or a high-fat (20%), high-sucrose (15%) diet (HFS) for 25 weeks. From week 16, animals were injected s.c. with 0.25 mg·kg^-1 selegiline (CON + S and HFS + S) or vehicle (CON, HFS) once daily. Whole body, subcutaneous and visceral fat was measured by CT, and glucose and insulin tolerance were tested. Expression of glucose transporters and chemokines was assessed by quantitative RT-PCR.

KEY RESULTS

Selegiline decreased whole body fat, subcutaneous- and visceral adiposity, measured by CT and epididymal fat weight in the HFS group, compared with HFS placebo animals, without influencing body weight. Oral glucose tolerance and insulin tolerance tests showed impaired glucose homeostasis in HFS and HFS + S groups, although insulin levels in plasma and pancreas were unchanged. HFS induced expression of Srebp-1c, Glut1 and Ccl3 in adipose tissue, which were alleviated by selegiline.

CONCLUSIONS AND IMPLICATIONS

Selegiline reduced adiposity, changes in adipose tissue energy metabolism and adipose inflammation induced by HFS diet without affecting the increased body weight, impairment of glucose homeostasis, or behaviour. These results suggest that selegiline could mitigate harmful effects of visceral adiposity.

Pressure-volume analysis reveals characteristic sex-related differences in cardiac function in a rat model of aortic banding-induced myocardial hypertrophy

Sex differences in pressure overload (PO)-induced left ventricular (LV) myocardial hypertrophy (LVH) have been intensely investigated. Nevertheless, sex-related disparities of LV hemodynamics in LVH were not examined in detail. Therefore, we aimed to provide a detailed characterization of distinct aspects of LV function in male and female rats during different stages of LVH. Banding of the abdominal aorta (AB) was performed to induce PO for 6 or 12 wk in male and female rats. Control animals underwent sham operation. The development of LVH was followed by serial echocardiography. Cardiac function was assessed by pressure-volume analysis. Cardiomyocyte hypertrophy and fibrosis were evaluated by histology. At week 6, increased LV mass index, heart weight-to-tibial length, cardiomyocyte diameter, concentric LV geometry, and moderate interstitial fibrosis were detected in both male and female AB rats, indicating the development of an early stage of LVH. Functionally, at this time, impaired active relaxation, increased contractility, and preserved ventricular-arterial coupling were observed in the AB groups in both sexes. In contrast, at week 12, progressive deterioration of LVH-associated structural and functional alterations occurred in male but not female animals with sustained PO. Accordingly, at this later stage, LVH was associated with eccentric remodeling, exacerbated fibrosis, and increased chamber stiffness in male AB rats. Furthermore, augmented contractility declined in male but not female AB animals, resulting in contractility-afterload mismatch. Maintained contractility augmentation, preserved ventricular-arterial coupling, and better myocardial compliance in female rats contribute to sex differences in LV function during the progression of PO-induced LVH. NEW & NOTEWORTHY We investigated sex differences in pressure overload-induced left ventricular myocardial hypertrophy for the first time on the functional level by pressure-volume analysis. We found that left ventricular hypertrophy was initially characterized by prolonged active relaxation, increased contractility, and maintained ventricular-arterial coupling in both sexes. However, at a later stage, augmented contractility declined in mate but not female rats, resulting in contractility-afterload mismatch. Furthermore, in male rats, increased myocardial stiffness also contributed to hypertrophy-associated diastolic dysfunction.

Pharmacological preconditioning with gemfibrozil preserves cardiac function after heart transplantation

While heart transplantation (HTX) is the definitive therapy of heart failure, donor shortage is emerging. Pharmacological activation of soluble guanylate cyclase (sGC) and increased cGMP-signalling have been reported to have cardioprotective properties. Gemfibrozil has recently been shown to exert sGC activating effects in vitro. We aimed to investigate whether pharmacological preconditioning of donor hearts with gemfibrozil could protect against ischemia/reperfusion injury and preserve myocardial function in a heterotopic rat HTX model. Donor Lewis rats received p.o. gemfibrozil (150 mg/kg body weight) or vehicle for 2 days. The hearts were explanted, stored for 1 h in cold preservation solution, and heterotopically transplanted. 1 h after starting reperfusion, left ventricular (LV) pressure-volume relations and coronary blood flow (CBF) were assessed to evaluate early post-transplant graft function. After 1 h reperfusion, LV contractility, active relaxation and CBF were significantly (p < 0.05) improved in the gemfibrozil pretreated hearts compared to that of controls. Additionally, gemfibrozil treatment reduced nitro-oxidative stress and apoptosis, and improved cGMP-signalling in HTX. Pharmacological preconditioning with gemfibrozil reduces ischemia/reperfusion injury and preserves graft function in a rat HTX model, which could be the consequence of enhanced myocardial cGMP-signalling. Gemfibrozil might represent a useful tool for cardioprotection in the clinical setting of HTX surgery soon.