Vardenafil protects isolated rat hearts at reperfusion dependent on GC and PKG.
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ABSTRACT:
SUBMITTER: Maas O
PROVIDER: S-EPMC2438966 | biostudies-other | 2008 May
REPOSITORIES: biostudies-other
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Project description:Despite efforts to elucidate its pathophysiology, ischemia-reperfusion injury lacks an effective preventative intervention. Because transient receptor potential cation channel subfamily M member 4 (TRPM4) is functionally expressed by many cell types in the cardiovascular system and is involved in the pathogenesis of various cardiovascular diseases, we decided to assess its suitability as a target of therapy. Thus, the aim of this study was to examine the possible cardioprotective effect of 9-phenanthrol, a specific inhibitor of TRPM4. Isolated Langendorff-perfused rat hearts were pretreated with Krebs-Henseleit (K-H) solution (control), 9-phenanthrol, or 5-hydroxydecanoate (5-HD, a blocker of the ATP-sensitive potassium channel) and then subjected to global ischemia followed by reperfusion with the K-H solution. To evaluate the extent of heart damage, lactate dehydrogenase (LDH) activity in the effluent solution was measured, and the size of infarcted area of the heart was measured by 2,3,5-triphenyltetrazolium chloride staining. In controls, cardiac contractility decreased, and LDH activity and the infarcted area size increased. In contrast, in hearts pretreated with 9-phenanthrol, contractile function recovered dramatically, and the infarcted area size significantly decreased. The cardioprotective effects of 9-phenanthrol was not completely blocked by 5-HD. These findings show that 9-phenanthrol exerts a cardioprotective effect against ischemia in the isolated rat heart and suggest that its mechanism of action is largely independent of ATP-sensitive potassium channels.
| S-EPMC3723883 | biostudies-literature
Project description:OBJECTIVE:To investigate the protective effect of melatonin against myocardial ischemia reperfusion (IR) injury in isolated rat hearts and explore the underlying mechanisms. METHODS:The isolated hearts from 40 male SD rats were randomly divided into 4 groups (n=10): the control group, where the hearts were perfused with KH solution for 175 min; IR group, where the hearts were subjected to global ischemia for 45 min followed by reperfusion for 120 min; IR+melatonin (Mel+IR) group, where melatonin (5 ?mol/L) was administered to the hearts 1 min before ischemia and during the first 5 min of reperfusion, followed by 115 min of reperfusion; and IR+2, 3-butanedione monoxime (IR+BDM) group, where the hearts were treated with BDM (20 mmol/L) in the same manner as melatonin treatment. Myocardial injury in the isolated hearts was assessed based on myocardial injury area, caspase-3 activity, and expressions of cytochrome C and cleaved caspase-3 proteins. Cardiac contracture was assessed using HE staining and by detecting lactate dehydrogenase (LDH) activity and the content of cardiac troponin I (cTnI) in the coronary outflow, measurement of left ventricular end-diastolic pressure (LVEDP) and electron microscopy. The content of ATP in the cardiac tissue was also determined. RESULTS:Compared with those in the control group, the isolated hearts in IR group showed significantly larger myocardial injury area and higher caspase-3 activity and the protein expressions of cytochrome C and cleaved caspase-3 with significantly increased LDH activity and cTnI content in the coronary outflow and elevated LVEDP at the end of reperfusion; HE staining showed obvious fractures of the myocardial fibers and the content of ATP was significantly decreased in the cardiac tissue; electron microscopy revealed the development of contraction bands. In the isolated hearts with IR, treatment with Mel or BDM significantly reduced the myocardial injury area, caspase-3 activity, and protein expressions of cytochrome C and cleaved caspase-3, obviously inhibited LDH activity, lowered the content of cTnI and LVEDP, reduced myocardial fiber fracture, and increased ATP content in the cardiac tissue. Both Mel and BDM inhibited the formation of contraction bands in the isolated hearts with IR injury. CONCLUSIONS:Mel can alleviate myocardial IR injury in isolated rat hearts by inhibiting cardiac contracture, the mechanism of which may involve the upregulation of ATP in the cardiac myocytes to lessen the tear of membrane and reduce cell content leakage.
| S-EPMC7386215 | biostudies-literature
Project description:AIM: To investigate the protective effect of tribulosin, a monomer of the gross saponins from Tribulus terrestris, against cardiac ischemia/reperfusion injury and the underlying mechanism in rats. METHODS: Isolated rat hearts were subjected to 30 min of ischemia followed by 120 min of reperfusion using Langendorff's technique. The hearts were assigned to seven groups: control, ischemia/reperfusion (I/R), treatment with gross saponins from Tribulus terrestris (GSTT) 100 mg/L, treatment with tribulosin (100, 10, and 1 nmol/L) and treatment with a PKC inhibitor (chelerythrine) (1 micromol/L). Infarct size was assessed by triphenyltetrazolium chloride staining. Malondialdehyde (MDA), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) contents as well as superoxide dismutase (SOD) and creatine kinase (CK) activities were determined after the treatment. Histopathological changes in the myocardium were observed using hematoxylin-eosin (H&E) staining. Apoptosis was detected with terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) assay. Bcl-2, Bax, caspase-3, and PKCepsilon protein expression were examined using Western blotting. RESULTS: Tribulosin treatment significantly reduced MDA, AST, CK and LDH contents, and increased the activity of SOD. The infarct size of I/R group was 40.21% of the total area. GSTT and various concentrations of tribulosin treatment decreased the infarct size to 24.33%, 20.24%, 23.19%, and 30.32% (P<0.01). Tribulosin treatment reduced the myocardial apoptosis rate in a concentration-dependent manner. Bcl-2 and PKCepsilon protein expression was increased after tribulosin preconditioning, whereas Bax and caspase-3 expression was decreased. In the chelerythrine group, Bcl-2 and PKCepsilon expression was decreased, whereas Bax and caspase-3 expression was increased. CONCLUSION: Tribulosin protects myocardium against ischemia/reperfusion injury through PKCepsilon activation.
| S-EPMC4002968 | biostudies-other
Project description:Phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway plays a key role in myocardial ischemia-reperfusion (I/R) injury. Mammalian target of rapamycin (mTOR), a downstream target of PI3K/AKT signaling, is necessary and sufficient to protect the heart from I/R injury. Inhaled anesthetic sevoflurane is widely used in cardiac surgeries because its induction and recovery are faster and smoother than other inhaled anesthetics. Sevoflurane proved capable of inducing postconditioning effects in the myocardium. However, the underlying molecular mechanisms for sevoflurane-induced postconditioning (SPC) were largely unclear. In the present study, we demonstrated that SPC protects myocardium from I/R injury with narrowed cardiac infarct focus, increased ATP content, and decreased cardiomyocyte apoptosis, which are mainly due to the activation of PI3K/AKT/mTOR signaling and the protection of mitochondrial energy metabolism. Application of dactolisib (BEZ235), a PI3K/mTOR dual inhibitor, abolishes the up-regulation of pho-AKT, pho-GSK, pho-mTOR, and pho-p70s6k induced by SPC, hence abrogating the anti-apoptotic effect of sevoflurane and reducing SPC-mediated protection of heart from I/R injury. As such, this study proved that PI3K/AKT/mTOR pathway plays an important role in SPC induced cardiac protection against I/R injury.
| S-EPMC4255182 | biostudies-literature
Project description:Recent studies have revealed that proper exercise can reduce the risk of chronic disease and is beneficial to the body. Peptides have been shown to play an important role in various pathological processes, including cardiovascular diseases. However, little is known about the role of exercise-induced peptides in cardiovascular disease. We aimed to explore the function and mechanism of TAG-23 peptide in reperfusion injury and oxidative stress. Treatment with TAG-23 peptide significantly improved cell viability, the mitochondrial membrane potential, and ROS levels and reduced LDH release, the apoptosis rate and caspase 3 activation in vitro. In vivo, TAG-23 ameliorated MI and heart failure induced by I/R or DOX treatment. Pull-down assays showed that TAG-23 can bind to PKG . The TAG-23-PKG complex inhibited PKG degradation through the UPS. We also identified cCbl as the E3 ligase of PKG and found that the interaction between these proteins was impaired by TAG-23 treatment. In addition, we provided evidence that TAG-23 mediated Lys48-linked polyubiquitination and subsequent proteasomal degradation. Our results reveal that a novel exercise-induced peptide, TAG-23, can inhibit PKG degradation by serving as a competitive binding peptide to attenuate the formation of the PKG-cCbl complex. Treatment with TAG-23 may be a new therapeutic approach for reperfusion injury.
| S-EPMC8233271 | biostudies-literature
Project description:BackgroundOur previous study indicated that Potentilla reptans root has a preconditioning effect by its antioxidant and anti-apoptotic effects in an isolated rat heart ischemia/reperfusion (IR) model. In the present study, we investigated the post-conditioning cardio-protective effects of Potentilla reptans and its active substances.MethodsThe ethyl acetate fraction of P. reptans root (Et) was subjected to an IR model under 30 min of ischemia and 100 min of reperfusion. To investigate the postconditioning effect, Et was perfused for 15 min at the early phase of reperfusion. RISK/SAFE pathway inhibitors, 5HD and L-NAME, were applied individually 10 min before the ischemia, either alone or in combination with Et during the early reperfusion phase. The hemodynamic factors and ventricular arrhythmia were calculated during the reperfusion. Oxidative stress, apoptosis markers, GSK-3β and SGK1 proteins were assessed at the end of experiments.ResultsEt postconditioning (Etpost) significantly reduced the infarct size, arrhythmia score, ventricular fibrillation incidence, and enhanced the hemodynamic parameters by decreasing the MDA level and increasing expression of Nrf2, SOD and CAT activities. Meanwhile, Etpost increased the BCl-2/BAX ratio and decreased Caspase-3 expression. The cardioprotective effect of Etpost was abrogated by L-NAME, Wortmannin (a PI3K/Akt inhibitor), and AG490 (a JAK/STAT3 inhibitor). Finally, Etpost reduced the expression of GSK-3β and SGK1 proteins pertaining to the IR group.ConclusionP. reptans reveals the post-conditioning effects via the Nrf2 pathway, NO release, and the RISK/SAFE pathway. Also, Etpost decreased apoptotic indexes by inhibiting GSK-3β and SGK1 expressions. Hence, our data suggest that Etpost can be a suitable natural candidate to protect cardiomyocytes during reperfusion injury.
| S-EPMC8620719 | biostudies-literature
Project description:Ischemic post-conditioning (iPoCo) by coronary re-occlusion/reperfusion during immediate reperfusion after prolonged myocardial ischemia reduces infarct size. Mechanical manipulation of culprit lesions, however, carries the risk of coronary microembolization which may obscure iPoCo's cardioprotection. Pharmacological post-conditioning with exogenous triiodothyronine (T3) could serve as an alternative conditioning strategy. Similar to iPoCo, T3 may activate cardioprotective prosurvival pathways. We aimed to study T3's impact on infarct size and its underlying signal transduction. Hearts were isolated from male Lewis rats (200-380 g), buffer-perfused and subjected to 30 min/120 min global zero-flow ischemia/reperfusion (I/R). In additional hearts, either iPoCo (2 × 30 s/30 s I/R) was performed or T3 (100-500 µg/L) infused at reperfusion. Infarct size was demarcated with triphenyl tetrazolium chloride staining and calculated as percent of ventricular mass. Infarct size was reduced with iPoCo to 16 ± 7% vs. 36 ± 4% with I/R only. The maximum infarct size reduction was observed with 300 µg/L T3 (14 ± 2%). T3 increased the phosphorylation of protein kinase B and mitogen extracellular-regulated-kinase 1/2, both key enzymes of the reperfusion injury salvage kinase (RISK) pathway. Pharmacological RISK blockade (RISK-BL) during reperfusion abrogated T3's cardioprotection (35 ± 10%). Adult ventricular cardiomyocytes were isolated from buffer-perfused rat hearts and exposed to 30 min/5 min hypoxia/reoxygenation (H/R); reoxygenation was initiated without or with T3, respectively, and without or with RISK-BL, respectively. Maximal preservation of viability was observed with 500 µg/L T3 after H/R (27 ± 4% of all cells vs. 5 ± 3% in time-matched controls). Again, RISK-BL abrogated protection (11 ± 3%). Mitochondria were isolated at early reperfusion from buffer-perfused rat hearts without or with iPoCo or 300 µg/L T3, respectively, at reperfusion. T3 improved mitochondrial function (i.e.: increased respiration, adenosine triphosphate production, calcium retention capacity, and decreased reactive oxygen species formation) to a similar extent as iPoCo. T3 at reperfusion reduces infarct size by activation of the RISK pathway. T3's protection is a cardiomyocyte phenomenon and targets mitochondria.
| S-EPMC8055637 | biostudies-literature
Project description:Aims: Activation and expression of large conductance calcium and voltage-activated potassium channel (BKCa) by pharmacological agents have been implicated in cardioprotection from ischemia-reperfusion (IR) injury possibly by regulating mitochondrial function. Given the non-specific effects of pharmacological agents, it is not clear whether activation of BKCa is critical to cardioprotection. In this study, we aimed to decipher the mechanistic role of BKCa in cardioprotection from IR injury by genetically activating BKCa channels. Methods and Results: Hearts from adult (3 months old) wild-type mice (C57/BL6) and mice expressing genetically activated BKCa (Tg-BKCa R207Q, referred as Tg-BKCa) along with wild-type BKCa were subjected to 20 min of ischemia and 30 min of reperfusion with or without ischemic preconditioning (IPC, 2 times for 2.5 min interval each). Left ventricular developed pressure (LVDP) was recorded using Millar's Mikrotip® catheter connected to ADInstrument data acquisition system. Myocardial infarction was quantified by 2,3,5-triphenyl tetrazolium chloride (TTC) staining. Our results demonstrated that Tg-BKCa mice are protected from IR injury, and BKCa also contributes to IPC-mediated cardioprotection. Cardiac function parameters were also measured by echocardiography and no differences were observed in left ventricular ejection fraction, fractional shortening and aortic velocities. Amplex Red® was used to assess reactive oxygen species (ROS) production in isolated mitochondria by spectrofluorometry. We found that genetic activation of BKCa reduces ROS after IR stress. Adult cardiomyocytes and mitochondria from Tg-BKCa mice were isolated and labeled with Anti-BKCa antibodies. Images acquired via confocal microscopy revealed localization of cardiac BKCa in the mitochondria. Conclusions: Activation of BKCa is essential for recovery of cardiac function after IR injury and is likely a factor in IPC mediated cardioprotection. Genetic activation of BKCa reduces ROS produced by complex I and complex II/III in Tg-BKCa mice after IR, and IPC further decreases it. These results implicate BKCa-mediated cardioprotection, in part, by reducing mitochondrial ROS production. Localization of Tg-BKCa in adult cardiomyocytes of transgenic mice was similar to BKCa in wild-type mice.
| S-EPMC6360169 | biostudies-literature
Project description:Although the optimal therapy for myocardial infarction includes reperfusion to restore blood flow to the ischemic area, myocardial injury after ischemia/reperfusion usually leads to an inflammatory response, oxidative stress, and cardiomyocyte apoptosis. In this study, rat adipose-derived stem cells were differentiated into low-thermogenic beige adipocytes (LBACs) and high-thermogenic beige adipocytes (HBACs) to study the different cardioprotective effects of heterogeneous expression of brown adipocytes. We found that antioxidant and antiapoptotic factors in H9c2 cardiomyocytes were upregulated by high levels of secreted FGF21 in HBAC conditioned medium (HBAC-CM), whereas FGF21 in HBAC-CM did not affect antioxidative or antiapoptotic cell death in H9c2 cardiomyocytes with Nrf2 knockdown. These results show that NRF2 mediates antioxidative and antiapoptotic effects through the HBAC-secreted factor FGF21. Consistent with this finding, the expression of antioxidant and antiapoptotic genes was upregulated by highly secreted FGF21 after HBAC-CM treatment compared to LBAC-CM treatment in H9c2 cardiomyocytes via NRF2 activation. Furthermore, HBAC-CM significantly attenuated ischemic rat heart tissue injury via NRF2 activation. Based on these findings, we propose that HBAC-CM exerts beneficial effects in rat cardiac ischemia/reperfusion injury by modulating NRF2 and has potential as a promising therapeutic agent for myocardial infarction.
| S-EPMC8833946 | biostudies-literature
Project description:Brain death (BD) can immunologically prime the donor organ and is thought to lead to exacerbated ischemia/reperfusion injury after transplantation. Using a newly developed mouse model of BD, we investigated the effect of donor BD on posttransplantation cardiac ischemia/reperfusion injury. We further investigated the therapeutic effect of a targeted complement inhibitor in recipients of BD donor hearts and addressed the clinical relevance of these studies by analyzing human heart biopsies from BD and domino (living) donors.Hearts from living or BD donor C57BL/6 mice were transplanted into C57BL/6 or BALB/c recipients. Recipient mice were treated with the complement inhibitor CR2-Crry or vehicle control (n=6). Isografts were analyzed 48 hours after transplantation for injury, inflammation, and complement deposition, and allografts were monitored for graft survival. Human cardiac biopsies were analyzed for complement deposition and inflammatory cell infiltration. In the murine model, donor BD exacerbated ischemia/reperfusion injury and graft rejection, as demonstrated by increased myocardial injury, serum cardiac troponin, cellular infiltration, complement deposition, inflammatory chemokine and cytokine levels, and by decreased graft survival. CR2-Crry treatment of recipients significantly reduced all measured outcomes in grafts from both BD and living donors compared with controls. Analysis of human samples documented the relevance of our experimental findings and revealed exacerbated complement deposition and inflammation in grafts from BD donors compared with grafts from living donors.BD exacerbates posttransplantation cardiac ischemia/reperfusion injury in mice and humans and decreases survival of mouse allografts. Furthermore, targeted complement inhibition in recipient mice ameliorates BD-exacerbated ischemia/reperfusion injury.
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