Does cardiac impairment develop in ischemic renal surgery in rats depending on the reperfusion time?

Background: Renal dysfunction is known to cause heart failure. However, renal dysfunction associated with kidney surgeries (mediated by reperfusion injury) that affects the cardiac physiological function, especially during the recovery and repair phase of renal surgery is unknown. Method: Male Wistar rats (238 ± 18 g) were subjected to renal sham and ischemia-reperfusion (IR-bilateral clamping for 15 min/45 min and reperfusion for 24 h/48 h/7 days) surgeries. At the end of the experiment, the heart was isolated from the animal (to exclude neurohormonal influence) and perfused for 60 min with Krebs-Hanseleit buffer to study the physiological changes. Result: Renal artery bilateral occlusion for 45 min that creates ischemia, followed by 24 h of reperfusion did not impart any significant cardiac physiological functional decline but 48 h of reperfusion exhibited a significant decline in cardiac hemodynamic indices (Rate pressure product in x104 mmHg*beats/min: Sham- 3.53 ± 0.19, I45_R48-2.82 ± 0.21) with mild tissue injury. However, 7 days of reperfusion inflict significant physiological decline (Rate pressure product in x104 mmHg*beats/min - 2.5 ± 0.14) and tissue injury (Injury score- 4 ± 1.5) in isolated rat hearts. Interestingly, when the renal artery bilateral occlusion time was reduced to 15 min the changes in the hearts were negligible after 7 days. Cellular level exploration reveals a positive relation between functional deterioration of mitochondria and elevated mitochondrial oxidative stress and inflammation with cardiac physiological decline and injury linked with renal ischemia-reperfusion surgery. Conclusion: Cardiac functional decline associated with renal surgery is manifested during renal repair or recovery. This decline depends on cardiac mitochondrial health, which is negatively influenced by the renal IR mediators and kidney function.

Cardiac damage following renal ischemia reperfusion injury increased with excessive consumption of high fat diet but enhanced the cardiac resistance to reperfusion stress in rat.

Renal ischemia-reperfusion (IR) injury inflicts remote cardiac dysfunction. Studies on rats fed with a high-fat diet (HD) showed contradictory results: some demonstrated increased sensitivity of the heart and kidney to IR injury, while others reported resistance. In this study, we examined cardiac dysfunction and compromised cardiac tolerance associated with renal IR in HD and standard diet (SD) fed rats. Male Wistar rats fed with HD or SD diet for 16 weeks were subjected to either renal sham or IR protocol (bilateral clamping for 45 min and reperfusion for 24 h). The hearts isolated from these rats were further subjected to normal perfusion or IR procedure to study cardiac response. Renal IR surgery negatively affected cardiac function with substantial changes in the cardiac tissues, like mitochondrial dysfunction, elevated oxidative stress, and inflammation. HD-fed rat hearts exhibited hypertrophy at the end of 16 weeks, and the consequential impact on the heart was higher in the animals underwent renal IR surgery than with sham surgery. However, the IR induction in the isolated heart from renal sham or renal IR operation showed significant tissue injury resistance and better physiological recovery in HD-fed rats. However, in SD-fed rats, only hearts from renal IR-operated rats showed resistance to cardiac IR, whereas hearts from renal sham-operated rats were more susceptible to IR damage. The augmented IR resistance in the heart with prior renal surgery was due to preserved mitochondrial bioenergetics function, reduced oxidative stress, and activation of the PI3K/AKT signaling axis.

Impaired renal ischemia reperfusion recovery after bilateral renal artery ligation in rats treated with adenine: role of renal mitochondria.

Vascular calcification (VC) and ischemia reperfusion (IR) injury is characterised to have mitochondrial dysfunction. However, the impact of dysfunctional mitochondria associated with vascular calcified rat kidney challenged to IR is not explored and is addressed in the present study. Male Wistar rats were treated with adenine for 20 days to induce chronic kidney dysfunction and VC. After 63 days, renal IR protocol was performed with subsequent recovery for 24 h and 7 days. Various mitochondrial parameters and biochemical assays were performed to assess kidney function, IR injury and its recovery. Adenine-induced rats with VC, decreased creatinine clearance (CrCl), and severe tissue injury demonstrated an increase in renal tissue damage and decreased CrCl after 24 h of IR (CrCl in ml: IR-0.220.02, VC-IR-0.050.01). Incidentally, the 24 h IR pathology in kidney was similar in both VC-IR and normal rat IR. But, the magnitude of dysfunction was higher with VC-IR due to pre-existing basal tissue alterations. We found severed deterioration in mitochondrial quantity and quality supported by low bioenergetic function in both VC basal tissue and IR challenged sample. However, post 7 days of IR, unlike normal rat IR, VC rat IR did not improve CrCl and corresponding mitochondrial damage in terms of quantity and its function were observed. Based on the above findings, we conclude that IR in VC rat adversely affect the post-surgical recovery, mainly due to the ineffective renal mitochondrial functional restoration from the surgery.

CABG Patients Develop Global DNA Hypermethylation, That Negatively Affect the Mitochondrial Function and Promote Post-Surgical Cognitive Decline: A Proof of Concept in Small Cohort.

Global DNA hypermethylation and mitochondrial dysfunction are reported to be associated with the development of mild cognitive decline (MCI). The present study aims to generate preliminary data that connect the above association with post-surgical coronary artery bypass grafting (CABG) cognitive decline in patients. Data were collected from 70 CABG patients and 25 age-matched controls. Cognitive function was assessed using the Montreal Cognitive Assessment (MOCA) test on day 1 (before surgery) and on the day of discharge. Similarly, blood was collected before and one day after the CABG procedure for mitochondrial functional analysis and expression of DNA methylation genes. Test analysis score suggested 31 (44%) patients had MCI before discharge. These patients showed a significant decrease in complex I activity and an increase in malondialdehyde levels (p < 0.001) from the control blood samples. Post-surgical samples showed a significant reduction in blood MT-ND1 mRNA expression from control and from pre-surgical samples (p < 0.005), along with elevated DNMT1 gene expression (p < 0.047), with an insignificant increase in TET1 and TET3 gene expression. Correlation analysis showed a significant positive relation between cognitive decline and elevated blood DNMT1 and declined blood complex I activity, signifying that cognitive decline experienced by post-surgical CABG patients is associated with increased DNMT1 expression and declined complex I activity. Based on the data, we conclude that both DNA hypermethylation and mitochondrial dysfunction are associated with post-CABG MCI, where the former is negatively correlated, and the latter is positively correlated with post-surgical MCI in CABG cases. Additionally, a multimarker approach that comprises MOCA, DNA methylation, DNMT, and NQR activities can be utilized to stratify the population that is sensitive to developing post-CABG MCI.

Recent advances in potential of Fisetin in the management of myocardial ischemia-reperfusion injury-A systematic review.

BACKGROUND: The primary therapeutic strategy in managing ischemic heart diseases is to restore the perfusion of the myocardial ischemic area by surgical methods that often result in an unavoidable injury called ischemia-reperfusion injury (IR). Fisetin is an effective flavonoid with antioxidant and anti-inflammatory properties, proven to be cardioprotective against IR injury in both in-vitro and invivo models, apart from its promising health benefits against cancer, diabetes, and neurodegenerative ailments. PURPOSE: The potential of fisetin in attenuating myocardial IR is inconclusive as the effectiveness of fisetin needs more understanding in terms of its possible target sites and underlying different mechanisms. Considering the surge in recent scientific interests in fisetin as a pharmacological agent, this review not only updates the existing preclinical and clinical studies with fisetin and its underlying mechanisms but also summarizes its possible targets during IR protection. METHODS: We performed a literature survey using search engines Pubmed, PMC, Science direct, Google, and research gate published across the years 2006-2021. The relevant studies were extracted from the databases with the combinations of the following keywords and summarized: myocardial ischemia-reperfusion injury, natural products, flavonoid, fisetin, PI3K, JAK-STAT, Nrf2, PKC, JNK, autophagy. RESULTS: Fisetin is reported to be effective in attenuating IR injury by delaying the clotting time, preserving the mitochondrial function, reducing oxidative stress, and inhibiting GSK 3ß. But it failed to protect diseased cardiomyocytes challenged to IR. As discussed in the current review, fisetin not only acts as a conventional antioxidant and anti-inflammatory agent to exert its biological effect but may also exert modulatory action on the cellular metabolism and adaptation via direct action on various signalling pathways that comprise PI3K, JAK-STAT, Nrf2, PKC, JNK, and autophagy. Moreover, the dosage of fisetin and co-morbidities like diabetes and obesity are found to be detrimental factors for cardioprotection. CONCLUSION: For further evaluation and smooth clinical translation of the fisetin molecule in IR treatment, researchers should pay close attention to the potential of fisetin to possibly alter the key cardioprotective pathways and dosage, as the efficacy of fisetin is tissue and cell type-specific and varies with different doses.

Long-term administration of fisetin was not as effective as short term in ameliorating IR injury in isolated rat heart.

The current study aims to determine the comparative efficacy of fisetin in reducing myocardial ischemia-reperfusion injury (IR) in isolated rat hearts when the drug was given either oral or intraperitoneal (ip) for short-term and long-term administration. Rats treated with fisetin (20 mg/kg-oral/ip) for short (30 min prior to surgery) and long (15 days prior to surgery followed by 1-day washout) duration were subjected to myocardial IR using Langendorf perfusion system. Hemodynamics, cardiac injury, mitochondrial functional assessment, and fisetin levels were estimated. Unlike the long-term administration of fisetin, the short-term treated-rat heart exhibited significant cardioprotection, measured via hemodynamic indices (RPP in mmHg × beats/min × 10 ^ 4: IR - 4 ± 0.1, FIPS - 2.49 ± 0.18, FIPL - 1.87 ± 0.14), reduced infarct size (in % area of infarct: IR - 38 ± 5, FIPS - 17 ± 1, FOS - 14 ± 2), improved mitochondrial ETC enzyme activity (NQR activity in IFM: FIPS - 0.25 ± 0.016, FIPL - 0.20 ± 0.02), and declined oxidative stress (GSH in IFM: FIPS - 1.52 ± 0.14, FIPL - 1.25 ± 0.22). However, no significant difference in the protection was observed between the animals treated with oral or intraperitoneally administered fisetin. Single dose of fisetin administration before IR protocol was more effective than 15 days of fisetin-treated drug followed by 1-day washout, thus may not be suitable for long-term dietary supplement for post-surgical cardiac rehabilitation.

Fisetin attenuates renal ischemia/reperfusion injury by improving mitochondrial quality, reducing apoptosis and oxidative stress.

Renal ischemic reperfusion (IR) injury is one of the major source of mortality and morbidity associated with acute kidney injury (AKI). Several flavonoids have shown to be renal protective against many nephrotoxic agents causing AKI. Fisetin, a promising flavonoid, is effective in the management of septic AKI, expected to ameliorate renal IR injury. The present study aimed to generate evidence for fisetin-mediated renal protection against IR injury. Male Wistar rats of 200-250 g were subjected to IR protocol by performing bilateral clamping for 45 min and reperfusion for 24 h. Fisetin was administrated 30 min (20 mg/kg b.wt, ip) before the surgery. Renal injury was evaluated by measuring the biomarkers in plasma, examining the ultra-structure of the kidney, and analyzing the apoptotic changes. Oxidative stress, antioxidant levels, and mitochondrial function were analyzed in the renal tissue. Fisetin administration significantly reduced the renal damages associated with IR by improving estimated glomerular filtration rate (eGFR: IR-0.35 ml/min, F_IR-9.03 ml/min), reducing plasma creatinine level (IR-2.2 mg/dl, F_IR-0.92 mg/dl), and lowering urinary albumin/creatinine ratio (IR-6.09 F_IR-2.16), caspase activity, decreased DNA fragmentation and reduced tubular injury score (IR- 11 F_IR-6.5). At the cellular level, fisetin significantly reduced renal oxidative stress and augmented the antioxidant levels. Fisetin was found to preserve mitochondrial electron transport chain activities and improved the ATP producing capacity in the renal tissue upon IR injury. Fisetin pretreatment attenuates renal IR injury by improving renal function, reducing the renal injury mediated by apoptosis, reducing free radical release, and augmenting mitochondrial function.

Hydrogen sulfide postconditioning rendered cardioprotection against myocardial ischemia-reperfusion injury is compromised in rats with diabetic cardiomyopathy.

The present study aimed to investigate the efficacy of hydrogen sulfide (H2S) post-conditioning (HPOC) against ischemia-reperfusion (I/R) challenged diabetic rat hearts with or without cardiomyopathy using the Langendorff perfusion system. Male Wistar rats were randomly divided into different groups such as normal, diabetes mellitus (DM), and diabetic cardiomyopathy (DCM). Hearts from these groups were subjected to normal perfusion, I/R, and HPOC and were analyzed for cardiac physiology, cardiomyocyte injury, mitochondrial function, oxidative stress, and H2S metabolism. The results showed that HPOC protocol reduced the cardiac injury and improved the haemodynamics in normal and DM effectively, but not in DCM (RPP in mmHg*beats/min*103: HPOC- 32 ± 2, DM-HPOC-19 ± 1, DCM-HPOC-6 ± 2, LVDP in mmHg: HPOC- 96 ± 3, DM-HPOC-73 ± 2, DCM-HPOC-50 ± 3). DCM rats at the basal level exhibited perturbed myocardial architecture, mitochondrial dysfunction, and impaired glycolytic flux that failed to improve by HPOC treatment after I/R. HPOC exhibited a nominal improvement in the gene expression and activities of the H2S metabolizing enzymes such as cystathionine beta-synthase, rhodanese, and cystathionine-gamma-lyase in DCM hearts. Collectively, our results suggest that altered myocardial architecture along with exacerbated oxidative stress and mitochondrial dysfunction contribute towards the failure of HPOC cardioprotection against I/R-induced myocardial tissue injury in DCM.

High-Fat Diet Increased Oxidative Stress and Mitochondrial Dysfunction Induced by Renal Ischemia-Reperfusion Injury in Rat.

Renal ischemia-reperfusion (IR) injury is one of the major causes of acute kidney injury influenced by the ischemic duration and the presence of comorbidities. Studies have reported that high-fat diet consumption can induce renal lipotoxicity and metabolic dyshomeostasis that can compromise the vital functions of kidney. This study aimed to evaluate the impact of a high-fat diet in the recovery of renal tissue from IR and explored the cellular pathology. In this study, 24 male Wistar rats were divided into two groups: normal diet (ND; n = 12) and high-fat diet (HD; n = 12), which were further subdivided into sham and IR groups at the end of the dietary regimen. The high-fat diet was introduced in 4-week-old rats and continued for 16 weeks. IR was induced by bilateral clamping of the renal peduncle for 45 min, followed by 24 h of reperfusion. Blood chemistry, estimated glomerular filtration rate (eGFR), mitochondrial function, and oxidative stress analysis were carried out to study the pathological changes. The rats fed with HD showed a decreased eGFR and elevated plasma creatinine, thereby compromised kidney function. Subcellular level changes in HD rats are deceased mitochondrial copy number, low PGC-1α gene expression, and declined electron transport chain (ETC) enzymes and adenosine triphosphate (ATP) level. Upon IR induction, HD rats exhibited severely impaired renal function (eGFR-0.09 ml/min) and elevated injury markers compared with ND rats. A histological analysis displayed increased tubular necrosis and cast formation in HD-IR in comparison to ND-IR. The oxidative stress and mitochondrial dysfunction were more prominent in HD-IR. In vitro protein translation assessment revealed impaired translational capacity in HD-IR mitochondria, which suggests mitochondrial changes with diet that may adversely affect the outcome of IR injury. High-fat diet consumption alters the normal renal function by modifying the cellular mitochondria. The renal changes compromise the ability of the kidney to recover from ischemia during reperfusion.

Evaluating the effects of carbon monoxide releasing molecule-2 against myocardial ischemia-reperfusion injury in ovariectomized female rats.

PURPOSE: Cardioprotective effect of carbon monoxide, a gasotransmitter against myocardial ischemia-reperfusion injury (I/R), is well established in preclinical studies with male rats. However, its ischemic tolerance in post-menopausal animals has not been examined due to functional perturbations at the cellular level. METHODS: The protective role of carbon monoxide releasing molecule-2 (CORM-2) on myocardial I/R was studied in female Wistar rats using the Langendorff apparatus. The animals were randomly divided into normal and ovariectomized (Ovx) female rats and were maintained 2 months post-surgery. Each group was further divided into 4 subgroups (n = 6/subgroup): normal, I/R, CORM-2-control (20 µmol/L), and CORM-2-I/R. The cardiac injury was estimated via myocardial infarct size, lactate dehydrogenase, and creatine kinase levels in coronary effluent and cardiac hemodynamic indices. Mitochondrial functional activity was assessed by measuring mitochondrial electron transport chain enzyme activities, swelling behavior, mitochondrial membrane potential, and oxidative stress. RESULTS: Hemodynamic indices were significantly lower in ovariectomized rat hearts than in normal rat hearts. Sixty minutes of reperfusion of ischemic heart exhibited deteriorated cardiac physiological recovery in both ovariectomized and normal groups, where prominent decline was observed in ovariectomized rat. However, preconditioning the isolated heart with CORM-2 improved hemodynamics parameters significantly in both ovariectomized and normal rat hearts challenged with I/R, but with a limited degree of protection in ovariectomized rat hearts. The protective effect of CORM-2 was further confirmed via a reduction in cardiac injury, preservation of mitochondrial enzymes, and reduction in oxidative stress in all groups. CONCLUSION: CORM-2 administration significantly attenuated myocardial I/R injury in ovariectomized rat hearts by attenuating I/R-associated mitochondrial perturbations and reducing oxidative stress.

Inhibition of PI3K/mTOR/KATP channel blunts sodium thiosulphate preconditioning mediated cardioprotection against ischemia-reperfusion injury.

Recent studies have shown that pre and postconditioning the heart with sodium thiosulfate (STS) attenuate ischemia-reperfusion (IR) injury. However, the underlying mechanism involved in the cardioprotective signaling pathway is not fully explored. This study examined the existing link of STS mediated protection (as pre and post-conditioning agents) with PI3K, mTOR, and mPTP signaling pathways using its respective inhibitors. STS was administered to the isolated perfused rat heart through Kreb's Heinselit buffer before ischemia (precondition: SIPC) and reperfusion (postcondition: SPOC) in the presence and absence of the PI3K, mTOR, and mPTP signaling pathway inhibitors (wortmannin, rapamycin, and glibenclamide respectively). SIPC failed to improve the IR injury-induced altered cardiac hemodynamics, increased infarct size, and the release of cardiac injury markers in the presence of these inhibitors. On the other hand, the SPOC protocol effectively rendered the cardioprotection even in the PI3K/mTOR/KATP inhibitors presence. Interestingly, the SIPC's identified mode of action viz reduction in oxidative stress and the preservation of mitochondrial function were lost in the inhibitors' presence. Based on the above results, we conclude that the underlying mechanism of SIPC mediated cardioprotection works via the PI3K/mTOR/KATP signaling pathway axis activation.

Attenuation of cardiac ischemia-reperfusion injury by sodium thiosulfate is partially dependent on the effect of cystathione beta synthase in the myocardium.

Our early studies have shown that sodium thiosulfate (STS) treatment attenuated the ischemia-reperfusion (IR)-induced injury in an isolated rat heart model by decreasing apoptosis, oxidative stress, and preserving mitochondrial function. Hydrogen sulfide, the precursor molecule is reported to have similar efficacy. This study aims to investigate the role of endogenous hydrogen sulfide in STS-mediated cardioprotection against IR in an isolated rat heart model. D, L-propargylglycine (PAG), an inhibitor of cystathionine γ-lyase was used as endogenous H2S blocker. In addition, we used the hypoxia-reoxygenation (HR) model to study the impact of STS in cardiomyocytes (H9C2) and fibroblast (3T3) cells. STS treatment to animal and cells prior to IR or HR decreased cell injury. The sensitivity of H9C2 and 3T3 cells towards HR (6 h hypoxia followed by 12 h reoxygenation) challenge varies, where, 3T3 cells exhibited higher cell death (54%). Cells treated with PAG prior to STS abrogate the protective effect in 3T3 (cell viability 61%) but not in H9C2 (cell viability 82%). Further evaluation in rat heart model showed partial recovery (46% RPP) of heart from those hearts pretreated with PAG prior to STS condition. In conclusion, we demonstrated that STS-mediated cardioprotection to IR-challenged rat heart is not fully dependent on endogenous H2S level and this dependency may be linked to higher fibroblast content in rat heart.