Protective effects of ginsenoside F2 on isoproterenol-induced myocardial infarction by activating the Nrf2/HO-1 and PI3K/Akt signaling pathways

BACKGROUND

Ginsenoside F2 (GF2) serves as the principal intestinal metabolite resulting from the oral intake of Panax ginseng and Panax quinquefolius, exhibiting antioxidative, hypolipidemic, antitumor, and anti-inflammatory properties. Nevertheless, its effect on myocardial infarction (MI) is still unknown.

PURPOSE

The purpose of this study is to investigate the protective effect and the underlying mechanisms of GF2 against isoproterenol (ISO)-induced MI.

METHODS

ISO-induced H9c2 cardiomyocytes and MI rat models were utilized as in vitro and in vivo models to evaluate the impact of anti-MI of GF2. The underlying mechanisms were investigated using a variety of methodologies, including electrocardiography, Western blot analysis, histopathological examination, immunofluorescence, immunohistochemistry, and ELISA techniques.

RESULTS

In vivo experiments, our results indicated that GF2 significantly ameliorated ISO-induced electrocardiographic (ECG) abnormalities, myocardial fiber necrosis, rupture, fibrosis of myocardial tissues, and suppressed cardiac enzyme activities. Meanwhile, GF2 notably raised the activity of antioxidant enzymes like CAT, GSH, and SOD. Furthermore, it downregulated Keap1 expression level while upregulating NQO1, Nrf2, and HO-1 expression levels. Additionally, GF2 suppressed the expression of the cleaved caspase-3 and pro-apoptotic protein Bax while promoting the expression of anti-apoptotic proteins Bcl-2, p-PI3K, and p-Akt. TUNEL fluorescence results also demonstrated that GF2 effectively inhibited cardiomyocyte apoptosis. Furthermore, consistent with the results of animal experiments, GF2 considerably attenuated ROS generation, changed apoptosis and mitochondrial function, and reduced oxidative stress in ISO-induced H9c2 cardiomyocytes through activating Nrf2/HO-1 and PI3K/Akt signaling pathways.

CONCLUSION

Taken together, GF2 ameliorated MI by preventing cardiocyte apoptosis, oxidative stress, and mitochondrial dysfunction via modulating the Nrf2/HO-1 and PI3K/Akt signaling pathways, showing potential as a treatment strategy for treating MI.

Doxorubicin-induced cardiotoxicity and risk factors

Doxorubicin (DOX) is an anthracycline antibiotic widely used as a chemotherapeutic agent to treat solid tumours and hematologic malignancies. Although useful in the treatment of cancers, the benefit of DOX is limited due to its cardiotoxic effect that is observed in a large number of patients. In the literature, there is evidence that the presence of various factors may increase the risk of developing DOX-induced cardiotoxicity. A better understanding of the role of these different factors in DOX-induced cardiotoxicity may facilitate the choice of the therapeutic approach in cancer patients suffering from various cardiovascular risk factors. In this review, we therefore discuss the latest findings in both preclinical and clinical research suggesting a link between DOX-induced cardiotoxicity and various risk factors including sex, age, ethnicity, diabetes, dyslipidaemia, obesity, hypertension, cardiovascular disease and co-medications.

Cardioprotective Effects of the 4-Week Aerobic Running Exercises Before Treatment with Doxorubicin in Rats

Doxorubicin is associated with cardiotoxicity, and physical exercise seeks to minimize the toxic effects of doxorubicin through physiological cardiac remodeling, as well as the reduction of oxidative stress, evidenced by previous studies. This study aimed to analyze whether running training before treatment with doxorubicin influences tolerance to physical exertion and cardiotoxicity. Thirty-nine male Wistar rats, aged 90 days and weighing between 250 and 300 g, were divided into 4 groups: Control (C), Doxorubicin (D), Trained (T), and Trained + Doxorubicin (TD). Animals in groups T and DT were submitted to treadmill running for 3 weeks, 5 times a week at 18 m/min for 20-30 min before treatment with doxorubicin. Animals in groups D and DT received intraperitoneal injections of doxorubicin hydrochloride three times a week for two weeks, reaching a total cumulative dose of 7.50 mg/kg. Our results show an increase in total collagen fibers in the D group (p = 0.01), but no increase in the TD group, in addition to the attenuation of the number of cardiac mast cells in the animals in the TD group (p = 0.05). The animals in the TD group showed maintenance of tolerance to exertion compared to group D. Therefore, running training attenuated the cardiac damage caused by the treatment with doxorubicin, in addition to maintaining the tolerance to exertion in the rats.

Metformin and Dapagliflozin Attenuate Doxorubicin-Induced Acute Cardiotoxicity in Wistar Rats: An Electrocardiographic, Biochemical, and Histopathological Approach

Doxorubicin is a widely used anticancer drug whose efficacy is limited due to its cardiotoxicity. There is no ideal cardioprotection available against doxorubicin-induced cardiotoxicity. This study aimed to investigate the anticipated cardioprotective potential of metformin and dapagliflozin against doxorubicin-induced acute cardiotoxicity in Wistar rats. At the beginning of the experiment, cardiac screening of experimental animals was done by recording an electrocardiogram (ECG) before allocating them into the groups. Thereafter, a total of thirty healthy adult Wistar rats (150-200 g) were randomly divided into five groups (n = 6) and treated for eight days as follows: group I (normal control), group II (doxorubicin control), group III (metformin 250 mg/kg/day), group IV (metformin 180 mg/kg/day), and group V (dapagliflozin 0.9 mg/kg/day). On the 7th day of the treatment phase, doxorubicin 20 mg/kg was administered intraperitoneal to groups II, III, IV, and V. On the 9th day (immediately after 48 h of doxorubicin administration), blood was collected from anesthetized animals for glucose, lipid profile, CK-MB & AST estimation, and ECG was recorded. Later, animals were sacrificed, and the heart was dissected for histopathological examination. We found that compared to normal control rats, CK-MB, AST, and glucose were significantly increased in doxorubicin control rats. There was a significant reversal of doxorubicin-induced hyperglycemia in the rats treated with metformin 250 mg/kg compared to doxorubicin control rats. Both metformin (180 mg/kg and 250 mg/kg) and dapagliflozin (0.9 mg/kg) significantly altered doxorubicin-induced ECG changes and reduced the levels of cardiac injury biomarkers CK-MB and AST compared to doxorubicin control rats. Metformin and dapagliflozin protected the cellular architecture of the myocardium from doxorubicin-induced myocardial injury. Current study revealed that both metformin and dapagliflozin at the FDA-recommended antidiabetic doses mitigated doxorubicin-induced acute cardiotoxicity in Wistar rats. The obtained data have opened the perspective to perform chronic studies and then to clinical studies to precisely consider metformin and dapagliflozin as potential chemoprotection in the combination of chemotherapy with doxorubicin to limit its cardiotoxicity, especially in patients with comorbid conditions like type II diabetes mellitus.

Synergistic cardioprotective effects of melatonin and deferoxamine through the improvement of ferritinophagy in doxorubicin-induced acute cardiotoxicity

Ferritinophagy is one of the most recent molecular mechanisms affecting cardiac function. In addition, it is one of the pathways by which doxorubicin, one of the anticancer drugs commonly used, negatively impacts the cardiac muscle, leading to cardiac function impairment. This side effect limits the use of doxorubicin. Iron chelators play an important role in hindering ferritinophagy. Antioxidants can also impact ferritinophagy by improving oxidative stress. In this study, it was assumed that the antioxidant function of melatonin could promote the action of deferoxamine, an iron chelator, at the level of ferritinophagy. A total of 42 male Wistar rats (150-200 g) were divided into seven groups (n = 6) which consisted of group I: control normal, group II: doxorubicin (Dox), group III: melatonin (Mel), group IV: deferoxamine (Des), group V: Mel + Dox, group VI: Des + Dox, and group VII: Mel + Des + Dox. Groups III, V and VII were orally pretreated with melatonin 20 mg/kg/day for 7 days. Groups IV, VI and VII were treated with deferoxamine at a 250 mg/kg/dose once on D4 before Dox was given. Doxorubicin was given at a 20 mg/kg ip single dose. On the 8th day, the rats were lightly anaesthetized for electrocardiography analysis and echocardiography. Serum samples were collected and then sacrificed for tissue sampling. The following biochemical assessments were carried out: PCR of NCOA4, IREB2, FTH1, SLC7A11, and GPX4; and ELISA for serum cTnI, serum transferrin, tissue GSH, and malondialdehyde. In addition, histopathological assessment of heart injury; immunostaining of caspase-3, Bax, and Bcl2; and physiological function assessment by ECG and ECHO were carried out. Doxorubicin-induced acute significant cardiac injury with increased ferritinophagy and apoptosis responded to single and combined prophylactic treatment, in which the combined treatment showed mostly the best results. In conclusion, using melatonin as an antioxidant with an iron chelator, deferoxamine, could hinder the hazardous cardiotoxic effect of doxorubicin. However, further studies are needed to detect the impact of higher doses of melatonin and deferoxamine with a prolonged treatment period.

Calcium Overload or Underload? The Effects of Doxorubicin on the Calcium Dynamics in Guinea Pig Hearts

The severe doxorubicin (DOXO) side effect of cardiomyopathy limits it clinical application as an effective anticancer drug. Although Ca²⁺ overload was postulated as one of the mechanisms for this toxicity, its role was, however, disputable in terms of the contractile dysfunction. In this work, the dynamics of the intracellular Ca²⁺ signal were optically mapped in a Langendorff guinea pig heart. We found that DOXO treatment: (1) Delayed the activation of the Ca²⁺ signal. With the reference time set at the peak of the action potential (AP), the time lag between the peak of the Ca²⁺ signal and AP (Ca-AP-Lag) was significantly prolonged. (2) Slowed down the intracellular Ca²⁺ releasing and sequestering process. Both the maximum rising (MRV) and falling (MFV) velocity of the Ca²⁺ signal were decreased. (3) Shortened the duration of the Ca²⁺ signal in one cycle of Ca²⁺ oscillation. The duration of the Ca²⁺ signal at 50% amplitude (CaD50) was significantly shortened. These results suggested a reduced level of intracellular Ca²⁺ after DOXO treatment. Furthermore, we found that the effect of tachypacing was similar to that of DOXO, and, interestingly, DOXO exerted contradictory effects on the tachypaced hearts: it shortened the Ca-AP-Lag, accelerated the MRV and MFV, and prolonged the CaD50. We, therefore, concluded that DOXO had a different effect on intracellular Ca²⁺. It caused Ca²⁺ underload in hearts with sinus rhythm; this might relate to the contractile dysfunction in DOXO cardiomyopathy. It led to Ca²⁺ overload in the tachypaced hearts, which might contribute to the Ca²⁺-overload-related toxicity.

Differential cardiotoxic electrocardiographic response to doxorubicin treatment in conscious versus anesthetized mice

INTRODUCTION

Doxorubicin (DOX), an anticancer drug used in chemotherapy, causes significant cardiotoxicity. This study aimed to investigate the effects of DOX on mouse cardiac electrophysiology, in conscious versus anesthetized state.

METHODS

Male and female C57BL/6 mice were injected with saline, 20 or 30 mg/kg DOX. ECGs were recorded 5 days post-injection in conscious and isoflurane anesthetized states. ECGs were analyzed using a custom MATLAB software to determine P, PR, QRS, QTc, and RR intervals as well as heart rate variability (HRV).

RESULTS

ECGs from the same mouse demonstrated P wave and QTc shortening as well as PR and RR interval prolongation in anesthetized versus conscious saline-treated mice. ECG response to DOX was also modulated by anesthesia. DOX treatment induced significant ECG modulation in female mice alone. While DOX20 treatment caused decrease in P and QRS durations, DOX30 treatment-induced QTc and RR interval prolongation in anesthetized but not in conscious female mice. These data suggest significant sex differences and anesthesia-induced differences in ECG response to DOX. HRV measured in time and frequency domains, a metric of arrhythmia susceptibility, was increased in DOX20-treated mice compared to saline.

CONCLUSIONS

This study for the first time identifies that the ECG response to DOX is modulated by anesthesia. Furthermore, this response demonstrated stark sex differences. These findings could have significant implications in clinical diagnosis of DOX cardiotoxicity.

Chia Seed Oil Ameliorates Doxorubicin-Induced Cardiotoxicity in Female Wistar Rats: An Electrocardiographic, Biochemical and Histopathological Approach

Doxorubicin (DOX) is a potent anti-cancer antibiotic that was widely used for treatment of various cancers. It produces free radicals which result in extreme dose-limiting cardiotoxicity. This study investigated the cardioprotective potential of chia seed oil, an active polyphenolic nutraceutical against doxorubicin-induced cardiotoxicity in Wistar rats. Twenty-four female Wistar rats were divided into four groups (n = 6) which consist of normal control, DOX control, test-A and test-B group. Animals were prophylactically treated with two different doses of test drug, i.e. chia seed oil 2.5 ml/kg/day and 5 ml/kg/day in test-A and test-B groups orally for 7 days. Doxorubicin (25 mg/kg; single dose) was administered intraperitoneally to DOX control, Test-A and Test-B animals on the seventh day to induce cardiotoxicity. ECG analysis was done before and after treatment. Besides ECG, CK, CK-MB, LDH, AST, MDA and GSH were analyzed. DOX had significantly altered ECG, CK, CK-MB, LDH, AST, MDA and GSH. Pre-treatment with chia seed oil significantly alleviated DOX-induced ECG changes and also guarded against DOX-induced rise of serum CK, CK-MB and AST levels. Chia seed oil alleviated histopathological alteration in DOX-treated rats. It also significantly inhibited DOX-induced GSH depletion and elevation of MDA. The present study revealed that chia seed oil exerts cardioprotection against doxorubicin-induced cardiotoxicity in female Wistar rats. Our study opens the perspective to clinical studies to precisely consider chia seed oil as a potential chemoprotectant nutraceutical in the combination chemotherapy with doxorubicin to limit its cardiotoxicity.

In Vivo and In Vitro Protective Effects of Rosmarinic Acid against Doxorubicin-Induced Cardiotoxicity

Doxorubicin (DOX) is an anticancer medicine that may trigger cardiomyopathy. Rosmarinic acid (RA) has shown antioxidant, anti-inflammatory, and anticancer effects. This investigation assessed the cardioprotective effect of RA on DOX-induced-toxicity in both in vivo and in vitro experiments. Male rats were randomized on 7 groups: (1) control, (2) DOX (2 mg/kg, per 48 h, 12d, i.p), (3) RA (40 mg/kg, 12d, i.p.), (4-6) RA (10, 20, 40 mg/kg, 16d, i.p.)+ DOX, (7) Vitamin E (200 mg/kg, per 48 h, 16d, i.p.) + DOX and then indices of cardiac function were estimated. Also, DOX and rosmarinic acid effects were examined on MCF7 cells (breast cancer cells line) to clarify that both cardiotoxicity and anticancer effects were analyzed. DOX increased heart to body weight ratio, RRI, QA, STI, QRS duration and voltage, attenuated HR, blood pressure, Max dP/dt, Min dP/dt, LVDP, enhanced MDA, declined GSH amount, and caused fibrosis and necrosis in cardiac tissue. Administration of RA ameliorated the toxic effects of DOX. In vitro studies showed that RA did not affect the cytotoxic effect of DOX. RA as an antioxidant, anti-inflammatory, and cardioprotective compound could be a promising compound to help minimize DOX-induced cardiotoxicity.

Image entropy-based label-free functional characterization of human induced pluripotent stem cell-derived 3D cardiac spheroids

Human induced pluripotent stem cell-derived cardiac spheroids (iPSC-CSs) in 3D possess tremendous potential for treating heart diseases and screening drugs for their cardiac effect. The beating pattern (including beating frequency and amplitude) of iPSC-CSs is a direct indicator of their health and function. However, detecting the beating pattern of 3D cardiac spheroid is not well studied and the probes commonly used for labeling cardiomyocytes for their beating pattern detection is toxic during long-term culture. Here, we reveal that the beating pattern of 3D iPSC-CSs can be conveniently detected/quantified by calculating the relative change of entropy in all the frames/images of non-fluorescent optical signal without labeling any cells. The entropy rate superpixel segmentation method is used for image segmentation in frames containing multiple or aggregated iPSC-CSs to identify individual iPSC-CSs, enabling rapid detection/quantification of the beating pattern of each iPSC-CS. Moreover, the responses of iPSC-CSs to both anticancer and cardiac drugs can be reliably detected with the image entropy-based label-free method in terms of their beating patterns. This novel label-free approach may be valuable for convenient and efficient functional evaluation of 3D and 2D cardiac constructs, which is important not only for drug screening but also the advancement of manufacturing functional cardiac constructs to treat heart diseases.

Hesperetin modulates the Sirt1/Nrf2 signaling pathway in counteracting myocardial ischemia through suppression of oxidative stress, inflammation, and apoptosis

Hesperetin (HSP) is a natural flavonoid that offers useful curative effects for cardiovascular diseases, but its effect on myocardial ischemia and its precise mechanism remains unclear. The aim of this study is to explore the potential cardioprotective mechanism of HSP on myocardial ischemia caused by isoproterenol (ISO). Adult male Kunming mice were randomly divided into five groups: control, ISO, low-dose HSP (L-HSP, 25 mg/kg/d), high-dose HSP (H-HSP, 50 mg/kg/d), and verapamil (VER) group. Treatment groups of mice received HSP or VER for seven days, and the groups other than the control group were injected with ISO (100 mg/kg/d) subcutaneously for two consecutive days to establish a model of myocardial ischemia. Electrocardiogram and heart-histology changes were used to assess changes in myocardial architecture. The activities and the content of oxidative stress markers and inflammatory cytokines were determined and assayed using kits respectively. The expressions of proteins associated with apoptosis and the Sirt1/Nrf2 pathway were evaluated by Western blotting. The results demonstrate that VER, L-HSP and H-HSP significantly reduced the J-point displacement, heart rate, cardiac pathomorphological changes, and the levels of creatine kinase, lactated dehydrogenase, malonaldehyde, interleukin-6, and tumor necrosis factor-α in serum while promoting the activation of superoxide dismutase, catalase, glutathione in serum in the ISO-treated animals. Furthermore, L-HSP and H-HSP also reversed the ISO-induced apoptosis and the changes in the Sirt1/Nrf2 signaling pathway, as evident from the levels of proteins Bax, Bcl-2, caspase-3, Sirt1, Nrf2, NQO-1, and HO-1. In conclusion, HSP plays a protective role in ISO-induced myocardial ischemia by modulating oxidative stress, inflammation, and apoptosis via Sirt1/Nrf2 pathway activation.

Evaluation of cardioprotective effects of carvedilol in dogs receiving doxorubicin chemotherapy: A prospective, randomized, double-blind, placebo controlled pilot study

The aim of this pilot study was to evaluate the cardioprotective effects of carvedilol in dogs receiving doxorubicin chemotherapy and provide suggestions to future studies based on results and limitations of our study. Thirteen dogs were randomized into two experimental groups: 6 dogs in carvedilol group and 7 dogs in placebo group. In carvedilol group, 0.39 mg/kg ± 0.04 twice-daily oral carvedilol was started on the day of the first doxorubicin treatment and continued throughout the chemotherapy protocol until the final cardiological evaluation. Cardiological evaluations were performed before the first doxorubicin administration and then 10 to 15 days after each subsequent dose. Troponin I and oxidative stress tests were performed with serum collected from dogs at the initial and final cardiological evaluation. Carvedilol produced some echocardiographic and electrocardiographic changes (reduced E velocity and E/IVRT ratio, as well reduced heart rate and increased PR and QT interval) due to its beta-block effect. In placebo group Doppler study showed a significant increase in mitral flow deceleration time (EDT), as well increased amplitude of the S wave in the right, and R wave in the left, precordial chest leads. There were significant difference in the EDT, E/IVRT and A' velocity, as well heart rate, PR interval and R wave in V4/CV6LU precordial chest lead between groups. In conclusion, some indexes of diastolic function and in precordial chest leads were less affected by doxorubicin in carvedilol than in control group. This suggests that carvedilol may have a beneficial effect in canine cancer patients receiving doxorubicin.

Methyl Gallate Attenuates Doxorubicin-Induced Cardiotoxicity in Rats by Suppressing Oxidative Stress

Doxorubicin-induced cardiotoxicity is the leading cause of morbidity and mortality among cancer survivors. The present study was aimed to investigate the cardioprotective potential of methyl gallate; an active polyphenolic nutraceutical, against doxorubicin-induced cardiotoxicity in Wistar rats. Twenty-four female Wistar rats (150-200 g) were divided into four groups (n = 6) which consist of normal control (group I), doxorubicin control (group II), test-A (group III), and test-B (group IV). Group III and group IV animals were prophylactically treated with methyl gallate 150 mg/kg/day and 300 mg/kg/day orally, respectively, for seven days. Doxorubicin (25 mg/kg; single dose) was administered through an intraperitoneal route to group II, III, and IV animals on the seventh day to induce acute cardiotoxicity. On the 8^th day, besides ECG analysis, serum CK, CK-MB, LDH, AST, MDA, and GSH were assayed. Following gross examination of isolated hearts, histopathological evaluation was performed by light microscopy. A significant (p < 0.05) cardiac injury, as well as oxidative stress, was observed in doxorubicin control rats in comparison to normal control rats. Methyl gallate at both the doses significantly (p < 0.05) reduced doxorubicin-induced ECG changes, dyslipidaemia, and elevation of CK, CK-MB, LDH, AST, MDA and increased GSH level. Methyl gallate reversed the doxorubicin-induced histopathological changes in the heart. The present study revealed that methyl gallate exerts cardioprotection against doxorubicin-induced cardiotoxicity in female Wistar rats by suppressing oxidative stress. Our study opens the perspective to clinical studies for consideration of methyl gallate as a potential chemoprotectant nutraceutical in the combination chemotherapy with doxorubicin to limit its cardiotoxicity.

Impact of Arterial Hypertension on Doxorubicin-Based Chemotherapy-Induced Subclinical Cardiac Damage in Breast Cancer Patients

Advances in oncologic therapies have allowed to achieve better outcomes and longer survival in many patients with breast cancer. Anthracyclines are cytotoxic antibiotics widely used in daily oncology practice. However, anthracyclines cause cardiotoxicity which is a limiting factor of its use. Cumulative dose of anthracyclines is the major cause of induced cardiotoxicity. According to previous clinical trials, the major predisposing high-risk factors for anthracycline-based chemotherapy-induced cardiotoxicity are age, body weight, female gender, radiotherapy, and other diseases such as diabetes and hypertension. Experimental studies in animals confirm that hypertension may be a significant factor predisposing anthracycline-based chemotherapy cardiotoxicity. The main objective of our study was to identify the effect of pre-existing arterial hypertension on the development of subclinical cardiac damage during or after doxorubicin-based chemotherapy in breast cancer patients. The study was performed prospectively between March 2016 and January 2017 in the Hospital of Lithuanian University of Health Sciences Kaunas Clinics Department of Oncology and Department of Cardiology. Data of 73 women with breast cancer treated with doxorubicin-based chemotherapy in outpatient clinic were analyzed. Statistically significant association between pre-existing arterial hypertension and left ventricular systolic dysfunction after completion of chemotherapy was observed (P < 0.004). Our study demonstrated that pre-existing arterial hypertension has a very important role in the development of anthracycline-based chemotherapy-induced cardiotoxicity, despite arterial hypertension control quality. Consequently, further studies evaluating impact of other risk factors and how early and sufficient management of arterial hypertension could influence the development of cardiotoxicity are needed to avoid permanent cardiac damage.

The role of metabolic diseases in cardiotoxicity associated with cancer therapy: What we know, what we would know

Metabolic diseases, such as obesity and type 2 diabetes, are known risk factors for cardiovascular (CV) diseases. Thus, patients with those comorbidities could be at increased risk of experiencing cardiotoxicity related to treatment with Anthracyclines and the other new generation targeted anticancer drugs. However, investigations addressing the mechanisms underlying the development of CV complications and poor outcome in such cohort of patients are still few and controversial. Given the importance of a personalized approach against chemotherapy-induced cardiomyopathy, this review summarizes our current knowledge on the pathophysiology of chemotherapy-induced cardiomyopathy and its association with obesity and type 2 diabetes. Along with clinical evidences, future perspectives of preclinical research around this field and its role in addressing important open questions, including the development of more proactive strategies for prevention, and treatment of cardiotoxicity during and after chemotherapy in the presence of metabolic diseases, is also presented.

Assessment of trazodone-induced cardiotoxicity after repeated doses in rats

Trazodone (TRZ) is an antidepressant drug commonly used in the treatment of depression, anxiety, and insomnia. Although some studies demonstrated the adverse effects of TRZ related to cardiovascular system, the conflicting results were observed in these studies. Therefore, we aimed to investigate the cardiac adverse effects of TRZ in rats at repeated doses in our study. In accordance with this purpose, TRZ was administered orally to rats at 5, 10, and 20 mg/kg doses for 28 days. Electrocardiogram records, serum aspartate aminotransferase (AST), lactate dehydrogenase, creatine kinase-myoglobin band, cardiac troponin-T (cTn-T) levels, DNA damage in cardiomyocytes, and histologic view of heart tissues were evaluated. In addition, glutathione (GSH) and malondialdehyde (MDA) levels were measured to determine the oxidative status of cardiac tissue after TRZ administration. Heart rate was decreased, PR interval was prolonged, and QRS and T amplitudes were decreased in 20 mg/kg TRZ-administered group compared to the control group. Serum AST and cTn-T levels were significantly increased in 10 and 20 mg/kg TRZ-administered rats with respect to control rats. DNA damage was significantly increased in these groups. Additionally, degenerative histopathologic findings were observed in TRZ-administered groups. Although there was no difference in MDA levels between groups, GSH levels were significantly decreased in 10 and 20 mg/kg TRZ-administered groups compared to the control group. Our results have shown that TRZ induced cardiotoxicity in rats dose-dependently. It is assumed that oxidative stress related to GSH depletion may be accompanied by these adverse effects.

TRPA1 mediates changes in heart rate variability and cardiac mechanical function in mice exposed to acrolein

Short-term exposure to ambient air pollution is linked with adverse cardiovascular effects. While previous research focused primarily on particulate matter-induced responses, gaseous air pollutants also contribute to cause short-term cardiovascular effects. Mechanisms underlying such effects have not been adequately described, however the immediate nature of the response suggests involvement of irritant neural activation and downstream autonomic dysfunction. Thus, this study examines the role of TRPA1, an irritant sensory receptor found in the airways, in the cardiac response of mice to acrolein and ozone. Conscious unrestrained wild-type C57BL/6 (WT) and TRPA1 knockout (KO) mice implanted with radiotelemeters were exposed once to 3ppm acrolein, 0.3ppm ozone, or filtered air. Heart rate (HR) and electrocardiogram (ECG) were recorded continuously before, during and after exposure. Analysis of ECG morphology, incidence of arrhythmia and heart rate variability (HRV) were performed. Cardiac mechanical function was assessed using a Langendorff perfusion preparation 24h post-exposure. Acrolein exposure increased HRV independent of HR, as well as incidence of arrhythmia. Acrolein also increased left ventricular developed pressure in WT mice at 24h post-exposure. Ozone did not produce any changes in cardiac function. Neither gas produced ECG effects, changes in HRV, arrhythmogenesis, or mechanical function in KO mice. These data demonstrate that a single exposure to acrolein causes cardiac dysfunction through TRPA1 activation and autonomic imbalance characterized by a shift toward parasympathetic modulation. Furthermore, it is clear from the lack of ozone effects that although gaseous irritants are capable of eliciting immediate cardiac changes, gas concentration and properties play important roles.

Variability in ozone-induced pulmonary injury and inflammation in healthy and cardiovascular-compromised rat models

The molecular bases for variability in air pollutant-induced pulmonary injury due to underlying cardiovascular (CVD) and/or metabolic diseases are unknown. We hypothesized that healthy and genetic CVD-prone rat models will exhibit exacerbated response to acute ozone exposure dependent on the type and severity of disease. Healthy male 12-14-week-old Wistar Kyoto (WKY), Wistar (WS) and Sprague Dawley (SD); and CVD-compromised spontaneously hypertensive (SH), Fawn-Hooded hypertensive (FHH), stroke-prone spontaneously hypertensive (SHSP), obese spontaneously hypertensive heart failure (SHHF) and obese JCR (JCR) rats were exposed to 0.0, 0.25, 0.5, or 1.0 ppm ozone for 4 h; pulmonary injury and inflammation were analyzed immediately following (0-h) or 20-h later. Baseline bronchoalveolar lavage fluid (BALF) protein was higher in CVD strains except for FHH when compared to healthy. Ozone-induced increases in protein and inflammation were concentration-dependent within each strain but the degree of response varied from strain to strain and with time. Among healthy rats, SD were least affected. Among CVD strains, lean rats were more susceptible to protein leakage from ozone than obese rats. Ozone caused least neutrophilic inflammation in SH and SHHF while SHSP and FHH were most affected. BALF neutrophils and protein were poorly correlated when considering the entire dataset (r = 0.55). The baseline and ozone-induced increases in cytokine mRNA varied markedly between strains and did not correlate with inflammation. These data illustrate that the degree of ozone-induced lung injury/inflammation response is likely influenced by both genetic and physiological factors that govern the nature of cardiovascular compromise in CVD models.

Comparison of the cardioprotective and renoprotective effects of the L/N-type calcium channel blocker, cilnidipine, in adriamycin-treated spontaneously-hypertensive rats

Cilnidipine is an L/N-type calcium channel blocker (CCB). The effects of cilnidipine on N-type channels give it unique organ-protective properties via the suppression of hyperactivity in the sympathetic nervous system (SNS) and renin-angiotensin-aldosterone system (RAAS). In the present study, we compared the effects of cilnidipine and amlodipine (an L-type CCB) on cardiac and renal functions in spontaneously-hypertensive rats injected with adriamycin (ADR). After the weekly administration of ADR for 3 weeks, spontaneously-hypertensive rats were orally administered cilnidipine (20 mg/kg per day), amlodipine (3 mg/kg per day), or vehicle once daily for 4 weeks. A control group received saline rather than ADR, followed by vehicle for 4 weeks. Cilnidipine and amlodipine produced similar reductions in blood pressure after 4 weeks. Cilnidipine ameliorated ADR-induced heart and kidney damage, whereas amlodipine slightly improved cardiac echocardiographic parameters, but did not protect against ADR-induced renal damage. Cilnidipine (but not amlodipine) suppressed the reflex SNS and RAAS hyperactivity caused by their antihypertensive effects. Furthermore, cilnidipine and amlodipine treatment decreased the urinary levels of adrenocortical hormones. The protective effects of cilnidipine against ADR-induced renal and cardiac dysfunction might be associated with its blockade of N-type calcium channels, in addition to its pleiotropic actions, which include the inhibition of the RAAS.

Pre-existing arterial hypertension as a risk factor for early left ventricular systolic dysfunction following (R)-CHOP chemotherapy in patients with lymphoma

Experimental studies in animals suggest that arterial hypertension may be a specific risk factor predisposing to anthracycline cardiotoxicity. The aim was determination of the effect of pre-existing arterial hypertension on the development of early left ventricular systolic dysfunction (LVSD) directly after rituximab, cyclophosphamide, doxorubicin, vincristin, prednisone ([R]-CHOP) chemotherapy in patients with lymphomas.The study included 208 patients with non-Hodgkin's lymphoma receiving conventional doxorubicin. LVSD was defined as a decrease of left ventricular ejection fraction below 50% and at least by 10 percentage points from baseline value. Patients with pre-existing hypertension more frequently developed new LVSD (19.7% vs. 6.6%; P = .004), pitting edema of the ankles (23.9% vs. 9.5%; P = .005), and nycturia (21.1% vs. 7.3%; P = .004) compared with patients without hypertension. As a consequence, the hypertension subgroup suffered from more delays of subsequent chemotherapy cycles (26.8% vs. 14.6%; P = .03), more reductions of doxorubicin doses (18.3% vs. 8.8%; P = .05), and premature discontinuations of chemotherapy (16.9% vs. 7.3%; P = .03). On logistic regression analyses, hypertension was one of the most important risk factors for developing new LVSD after (R)-CHOP chemotherapy.Arterial hypertension confers a significant risk of early LVSD in lymphoma patients treated with (R)-CHOP chemotherapy, interfering with its recommended schedule of administration.

Doxorubicin has in vivo toxicological effects on ex vivo cultured mesenchymal stem cells

Doxorubicin (dox) is an effective chemotherapeutic agent that leads to cardiotoxicity. An alternative treatment for dox-cardiotoxicity is autologous mesenchymal stem cells (MSCs) transplantation. It remains unclear if dox has deleterious effects on MSCs from subjects under chemotherapy, therefore this study aimed to evaluate dox in vivo toxicological effects on ex vivo cultured MSCs, inferring whether autologous transplantation may be an alternative treatment in patients who are exposed to the drug. Wistar rats received either dox or saline. Following treatments, animals were sacrificed and bone marrow MSCs were isolated, characterized for cell surface markers and assessed according to their viability, alkaline phosphatase production, and proliferation kinetics. Moreover, MSCs were primed to cardiac differentiation and troponin T and connexin 43 expressions were evaluated. Compared to control, undifferentiated MSCs from dox group kept the pattern for surface marker and had similar viability results. In contrast, they showed lower alkaline phosphatase production, proliferation rate, and connexin 43 expression. Primed MSCs from dox group showed lower troponin T levels. It was demonstrated a toxic effect of dox in host MSCs. This result renders the possibility of autologous MSCs transplantation to treat dox-cardiotoxicity, which could be a non-suitable option for subjects receiving such antineoplastic agent.

Doxorubicin Cardiotoxicity and Cardiac Function Improvement After Stem Cell Therapy Diagnosed by Strain Echocardiography

Doxorubicin (Dox) is one of the most effective chemotherapeutic agents; however, it causes dose-dependent cardiotoxicity. Evaluation of left ventricular function relies on measurements based on M-mode echocardiography. A new technique based on quantification of myocardial motion and deformation, strain echocardiography, has been showed promising profile for early detection of cardiac dysfunction. Different therapy strategies, such as flavonoid plant extracts and stem cells, have been investigated to improve heart function in toxic cardiomyopathy. This work aimed to assess early cardiac function improvement after treatments with either flavonoid extract from Camellia sinensis or mesenchymal stem cells in Dox cardiotoxicity using strain echocardiography. Twenty Wistar rats were randomly assigned to four groups. They received water (control, Dox, Dox + stem cells) or 100 mg/kg C. sinensis extract (Dox + C. sinensis) via gavage, daily, for four weeks. Animals also received saline (control) or 5 mg/kg doxorubicin (Dox, Dox + C. sinensis, Dox + stem cells) via intraperitoneal injection, weekly, for four weeks. Stem cells were injected (3 × 10⁶ cells) through tail vein prior the beginning of the experiment (Dox + stem cells). Animals were evaluated by hematological, electrocardiography, echocardiography, and histopathological examinations. Dox cardiotoxicity was only diagnosed with strain echocardiography, detecting a decrease in ventricular function. C. sinensis extract did not prevent ventricular dysfunction induced by Dox. However, strain echocardiography examination revealed that Dox cardiotoxicity was significantly suppressed in rats treated with stem cells. In conclusion, strain echocardiography was able to detect precocity signs of heart failure and stem cell therapy showed cardioprotection effect against Dox cardiotoxicity.

Berberine attenuates doxorubicin-induced cardiotoxicity in mice

This study investigated the effects of berberine, a natural alkaloid, on doxorubicin-induced cardiotoxicity in mice. Mice were injected intraperitoneally with saline 10 ml/kg (n = 10), doxorubicin 2.5 mg/kg (n = 10), 60 mg/kg berberine 1 h before doxorubicin 2.5 mg/kg (n = 10), or 60 mg/kg berberine alone (n = 10) every other day for 14 days. Body weight, general condition and mortality were recorded over the 14-day study period. Electro cardiography was performed before the start of treatment and after 14 days and plasma lactate dehydrogenase (LDH) activity was measured after 14 days. At the end of the study period the heart was excised and examined histologically. An increase in mortality, an initial decrease in body weight, increased LDH activity, prolongation of QRS duration and increased myocardial injury were seen in the doxorubicin-treated group compared with the saline control group. These changes were significantly attenuated by pretreatment with berberine. The study suggests that berberine may have a potential protective role against doxorubicin-induced cardiotoxicity in mice.

Let-7 g is involved in doxorubicin induced myocardial injury

OBJECTIVES

To investigate whether let-7 g (miRNA) was involved in doxorubicin-induced cardiotoxicity.

METHODS

Rats were treated with doxorubicin at increasing doses (0mg/kg, 6 mg/kg, 12 mg/kg, 18 mg/kg). Heart rate, pulse pressure and plasma cardiac troponin T concentrations were measured. Primary cultured myocardial cells were incubated with DOX at increasing concentrations (0 μmol/l, 0.004 μmol/l, 0.02 μmol/l, 0.1 μmol/l, 0.5 μmol/l) for 24h. Cellular viability and the beat frequency were measured. For both rats and cultured cells, miRNA content was measured by real-time reverse-transcription PCR.

RESULTS

All DOX-treated rats had a decrease in heart rate, an increase in pulse pressure compared with control group after injections (p<0.05). Concentration of cTnT was increased significantly in 18 mg/kg group. Content of let-7 g decreased significantly (p<0.05) in 18 mg/kg group in vivo and all the doxorubicin treated group in vitro.

CONCLUSIONS

The down regulation of let-7 g in the myocardial-injury model suggests that let-7 g may play an important role in the development of cardiac disease.

Effect of phospholipid composition on pharmacokinetics and biodistribution of epirubicin liposomes

The effects of phospholipid composition on the pharmacokinetics (PK) and biodistribution of epirubicin (EPI) liposomes, as well as the in vitro macrophage uptake of various liposome formulations, were investigated. Three liposome formulations were investigated: HSPC:Chol (L-EPI; 5:4 molar ratio), HSPC:Chol:DSPG (D-EPI; 5:4:1 molar ratio), and HSPC:Chol:DSPG:DSPE-mPEG(2000) (S-EPI; 5:4:1:0.3 molar ratio). Small unilamellar liposomes were prepared by the modified thin-film hydration method with extrusion through polycarbonate filters, and EPI was remote loaded into liposomes by the transmembrane ammonium sulfate gradient method. Macrophages were used to evaluate in vitro the cellular uptake of EPI-loaded liposomes. The following decreasing order of uptake amount was observed: L-EPI>D-EPI>S-EPI. D-EPI showed a relatively low level of uptake, probably because of the steric hindrance provided by the glycerol head group on DSPG, protecting it from the direct recognization by cell-membrane receptors. With the presence of serum, uptake values for all liposome formulations were increased for the activation of the complement system. In the PK study, S-EPI showed significantly prolonged circulating time and reduced clearance. The following increasing order of area under the concentration versus time curve was observed among the various liposome formulations: L-EPI<D-EPI<S-EPI. The biodistribution study indicated that S-EPI decreased drug disposition in the liver, spleen, lung, and heart and increased that in the kidney with respect to the other liposomes. The encouraging property of S-EPI, in terms of prolonging circulating time and reducing heart toxicity, might describe a promising perspective toward clinical application, and all the results would support further research into liposome-based drug carriers.

ST depression, arrhythmia, vagal dominance, and reduced cardiac micro-RNA in particulate-exposed rats

Recently, investigators demonstrated associations between fine particulate matter (PM)-associated metals and adverse health effects. Residual oil fly ash (ROFA), a waste product of fossil fuel combustion from boilers, is rich in the transition metals Fe, Ni, and V, and when released as a fugitive particle, is an important contributor to ambient fine particulate air pollution. We hypothesized that a single-inhalation exposure to transition metal-rich PM will cause concentration-dependent cardiovascular toxicity in spontaneously hypertensive (SH) rats. Rats implanted with telemeters to monitor heart rate and electrocardiogram were exposed once by nose-only inhalation for 4 hours to 3.5 mg/m(3), 1.0 mg/m(3), or 0.45 mg/m(3) of a synthetic PM (dried salt solution), similar in composition to a well-studied ROFA sample consisting of Fe, Ni, and V. Exposure to the highest concentration of PM decreased T-wave amplitude and area, caused ST depression, reduced heart rate (HR), and increased nonconducted P-wave arrhythmias. These changes were accompanied by increased pulmonary inflammation, lung resistance, and vagal tone, as indicated by changes in markers of HR variability (increased root of the mean of squared differences of adjacent RR intervals [RMSSD], low frequency [LF], high frequency [HF], and decreased LF/HF), and attenuated myocardial micro-RNA (RNA segments that suppress translation by targeting messenger RNA) expression. The low and intermediate concentrations of PM had less effect on the inflammatory, HR variability, and micro-RNA endpoints, but still caused significant reductions in HR. In addition, the intermediate concentration caused ST depression and increased QRS area, whereas the low concentration increased the T-wave parameters. Thus, PM-induced cardiac dysfunction is mediated by multiple mechanisms that may be dependent on PM concentration and myocardial vulnerability (this abstract does not reflect the policy of the United States Environmental Protection Agency).

A single exposure to particulate or gaseous air pollution increases the risk of aconitine-induced cardiac arrhythmia in hypertensive rats

Epidemiological studies demonstrate an association between arrhythmias and air pollution. Aconitine-induced cardiac arrhythmia is widely used experimentally to examine factors that alter the risk of arrhythmogenesis. In this study, Wistar-Kyoto (WKY) and spontaneously hypertensive (SH) rats acutely exposed to synthetic residual oil fly ash (s-ROFA) particles (450 mug/m(3)) were "challenged" with aconitine to examine whether a single exposure could predispose to arrhythmogenesis. Separately, SH rats were exposed to varied particulate matter (PM) concentrations (0.45, 1.0, or 3.5 mg/m(3) s-ROFA), or the irritant gas acrolein (3 ppm), to better assess the generalization of this challenge response. Rather than directly cause arrhythmias, we hypothesized that inhaled air pollutants sensitize the heart to subsequent dysrhythmic stimuli. Twenty-four hour postexposure, urethane-anesthetized rats were monitored for heart rate (HR), electrocardiogram, and blood pressure (BP). SH rats had higher baseline HR and BP and significantly longer PR intervals, QRS duration, QTc, and JTc than WKY rats. PM exposure caused a significant increase in the PR interval, QRS duration, and QTc in WKY rats but not in SH rats. Heart rate variability was significantly decreased in WKY rats after PM exposure but increased in SH rats. Cumulative dose of aconitine that triggered arrhythmias in air-exposed SH rats was lower than WKY rats and even lower for each strain postexposure. SH rats exposed to varied concentrations of PM or acrolein developed arrhythmia at significantly lower doses of aconitine than controls; however, there was no PM concentration-dependent response. In conclusion, a single exposure to air pollution may increase the sensitivity of cardiac electrical conduction to disruption. Moreover, there seem to be host factors (e.g., cardiovascular disease) that increase vulnerability to triggered arrhythmias regardless of the pollutant or its concentration.