Haloperidol affects coupling between QT and RR intervals in guinea pig isolated heart.

Prolonged QT interval is an independent risk factor for development of ventricular arrhythmias. Haloperidol is one of the drugs inducing QT prolongation. Previous studies showed that haloperidol affects not only QT duration but also heart rate (RR interval). The present work focused on relationship between QT and RR and its changes under acute and chronic haloperidol administration. The study included 14 male guinea pigs divided into control and haloperidol-treated group. After 21-days administration of haloperidol or vehiculum, electrograms in isolated hearts were recorded. QT/RR and dQT/dRR coupling were calculated. Chronic haloperidol administration significantly decreases the coupling between QT and RR. Acute haloperidol exposure significantly decreases the dQT/dRR coupling in both treated and untreated guinea pig hearts. Flatter QT/RR relationship reveals a lack of QT adaptation to increased heart rate. It should be emphasized that in such situation ECG recording will not show significant QT prolongation evaluated according to clinical rules. However, if QT interval does not adapt to increased heart rate sufficiently, the risk of ventricular arrhythmias may be increased despite practically normal QT interval length. The results are supported by findings in biochemical analyses, which proved eligibility of the used model.

Haloperidol Affects Plasticity of Differentiated NG-108 Cells Through σ1R/IP3R1 Complex.

Haloperidol is an antipsychotic agent that primarily acts as an antagonist of D2 dopamine receptors. Besides other receptor systems, it targets sigma 1 receptors (σ1Rs) and inositol 1,4,5-trisphosphate receptors (IP3Rs). Aim of this work was to investigate possible changes in IP3Rs and σ1Rs resulting from haloperidol treatment and to propose physiological consequences in differentiated NG-108 cells, i.e., effect on cellular plasticity. Haloperidol treatment resulted in up-regulation of both type 1 IP3Rs (IP3R1s) and σ1Rs at mRNA and protein levels. Haloperidol treatment did not alter expression of other types of IP3Rs. Calcium release from endoplasmic reticulum (ER) mediated by increased amount of IP3R1s elevated cytosolic calcium and generated ER stress. IP3R1s were bound to σ1Rs, and translocation of this complex from ER to nucleus occurred in the group of cells treated with haloperidol, which was followed by increased nuclear calcium levels. Haloperidol-induced changes in cytosolic, reticular, and nuclear calcium levels were similar when specific σ1 blocker -BD 1047- was used. Changes in calcium levels in nucleus, ER, and cytoplasm might be responsible for alterations in cellular plasticity, because length of neurites increased and number of neurites decreased in haloperidol-treated differentiated NG-108 cells.

Effect of increased left ventricle mass on ischemia assessment in electrocardiographic signals: rabbit isolated heart study.

BACKGROUND: Detailed quantitative analysis of the effect of left ventricle (LV) hypertrophy on myocardial ischemia manifestation in ECG is still missing. The associations between both phenomena can be studied in animal models. In this study, rabbit isolated hearts with spontaneously increased LV mass were used to evaluate the effect of such LV alteration on ischemia detection criteria and performance. METHODS: Electrophysiological effects of increased LV mass were evaluated on sixteen New Zealand rabbit isolated hearts under non-ischemic and ischemic conditions by analysis of various electrogram (EG) parameters. To reveal hearts with increased LV mass, LV weight/heart weight ratio was proposed. Standard paired and unpaired statistical tests and receiver operating characteristics analysis were used to compare data derived from different groups of animals, monitor EG parameters during global ischemia and evaluate their ability to discriminate between unchanged and increased LV as well as non-ischemic and ischemic state. RESULTS: Successful evaluation of both increased LV mass and ischemia is lead-dependent. Particularly, maximal deviation of QRS and area under QRS associated with anterolateral heart wall respond significantly to even early phase (the 1st-3rd min) of ischemia. Besides ischemia, these parameters reflect increased LV mass as well (with sensitivity reaching approx. 80%). However, the sensitivity of the parameters to both phenomena may lead to misinterpretations, when inappropriate criteria for ischemia detection are selected. Particularly, use of cut-off-based criteria defined from control group for ischemia detection in hearts with increased LV mass may result in dramatic reduction (approx. 15%) of detection specificity due to increased number of false positives. Nevertheless, criteria adjusted to particular experimental group allow achieving ischemia detection sensitivity of 89-100% and specificity of 94-100%, respectively. CONCLUSIONS: It was shown that response of the heart to myocardial ischemia can be successfully evaluated only when taking into account heart-related factors (such as LV mass) and other methodological aspects (such as recording electrodes position, selected EG parameters, cut-off criteria, etc.). Results of this study might be helpful for developing new clinical diagnostic strategies in order to improve myocardial ischemia detection in patients with LV hypertrophy.

Long-Term Haloperidol Treatment Prolongs QT Interval and Increases Expression of Sigma 1 and IP3 Receptors in Guinea Pig Hearts.

Haloperidol is a neuroleptic drug used for a medication of various psychoses and deliria. Its administration is frequently accompanied by cardiovascular side effects, expressed as QT interval prolongation and occurrence of even lethal arrhythmias. Despite these side effects, haloperidol is still prescribed in Europe in clinical practice. Haloperidol binds to sigma receptors that are coupled with inositol 1,4,5-trisphosphate (IP3) receptors. Sigma receptors are expressed in various tissues, including heart muscle, and they modulate potassium channels. Together with IP3 receptors, sigma receptors are also involved in calcium handling in various tissues. Therefore, the present work aimed to study the effects of long-term haloperidol administration on the cardiac function. Haloperidol (2 mg/kg once a day) or vehiculum was administered by intraperitoneal injection to guinea pigs for 21 consecutive days. We measured the responsiveness of the hearts isolated from the haloperidol-treated animals to additional application of haloperidol. Expression of the sigma 1 receptor and IP3 receptors was studied by real time-PCR and immunohistochemical analyses. Haloperidol treatment caused the significant decrease in the relative heart rate and the prolongation of QT interval of the isolated hearts from the haloperidol-treated animals, compared to the hearts isolated from control animals. The expression of sigma 1 and IP3 type 1 and type 2 receptors was increased in both atria of the haloperidol-treated animals but not in ventricles. The modulation of sigma 1 and IP3 receptors may lead to altered calcium handling in cardiomyocytes and thus contribute to changed sensitivity of cardiac cells to arrhythmias.

Hydroxyl radicals' production and ECG parameters during ischemia and reperfusion in rat, guinea pig and rabbit isolated heart.

Ischemic and reperfusion injury is a serious condition related to numerous biochemical and electrical abnormalities of the myocardium. It has been repeatedly studied in various animal models. In this study, the production of hydroxyl radicals and electrophysiological parameters were compared in three species. Rat, guinea pig and rabbit isolated hearts were perfused according to Langendorff under strictly identical conditions. The heart rate and arrhythmia were monitored during ischemia and reperfusion periods at defined time intervals; the production of hydroxyl radical was determined by HPLC as 2.5-dihydroxybenzoic acid (2.5-DHBA) formed by salicylic acid hydroxylation. Relationship between arrhythmias and production of 2.5-DHBA was studied. The inter-species differences were observed in timing of arrhythmias onset and their severity, and in the production of 2.5-DHBA in both ischemia and reperfusion. The most considerable changes were observed in rats, where arrhythmias appeared early and with highest severity during ischemia on one side and the regular rhythm was restored early and completely during reperfusion. The corresponding changes in the production of 2.5-DHBA were observed. It can be concluded that rat isolated heart is the most suitable model for evaluation of ischemia/reperfusion injury under given experimental conditions.

Golden Standard or Obsolete Method? Review of ECG Applications in Clinical and Experimental Context.

Cardiovascular system and its functions under both physiological and pathophysiological conditions have been studied for centuries. One of the most important steps in the cardiovascular research was the possibility to record cardiac electrical activity. Since then, numerous modifications and improvements have been introduced; however, an electrocardiogram still represents a golden standard in this field. This paper overviews possibilities of ECG recordings in research and clinical practice, deals with advantages and disadvantages of various approaches, and summarizes possibilities of advanced data analysis. Special emphasis is given to state-of-the-art deep learning techniques intensely expanded in a wide range of clinical applications and offering promising prospects in experimental branches. Since, according to the World Health Organization, cardiovascular diseases are the main cause of death worldwide, studying electrical activity of the heart is still of high importance for both experimental and clinical cardiology.

Fatty Acid Supplementation Affects Skin Wound Healing in a Rat Model.

Polyunsaturated fatty acids (PUFA) play an important role in reparative processes. The ratio of PUFAs n-3 to n-6 may affect wound healing. The study aimed to evaluate the effect of dietary supplementation with n-3 and n-6 PUFA in two proportions on skin wounds in laboratory rats. Adult male Wistar rats received 20% fat emulsion with a ratio of 1.4:1 (group A) or 4.3:1 (group B) for n-3:n-6 PUFAs at a daily dose of 1 mL/kg. The control group received water under the same conditions. The animals were supplemented a week before and a week after the skin excision performed on the back. The level of wound closure, various parameters of oxidative stress, and plasma fatty acids composition were evaluated. Wound tissue samples were examined by electron microscopy. The administration of fat emulsions led to significant changes in plasma polyunsaturated fatty acid composition. The increased production of reactive nitrogen species, as well as more numerous newly formed blood vessels and a greater amount of highly organized collagen fibrils in both groups A and B may indicate more intensive healing of the skin wound in rats supplemented with polyunsaturated fatty acids in high n-3:n-6 ratio.

Di-4-ANEPPS Modulates Electrical Activity and Progress of Myocardial Ischemia in Rabbit Isolated Heart.

AIMS: Although voltage-sensitive dye di-4-ANEPPS is a common tool for mapping cardiac electrical activity, reported effects on electrophysiological parameters are rather. The main goals of the study were to reveal effects of the dye on rabbit isolated heart and to verify, whether rabbit isolated heart stained with di-4-ANEPPS is a suitable tool for myocardial ischemia investigation. METHODS AND RESULTS: Study involved experiments on stained (n = 9) and non-stained (n = 11) Langendorff perfused rabbit isolated hearts. Electrophysiological effects of the dye were evaluated by analysis of various electrogram (EG) parameters using common paired and unpaired statistical tests. It was shown that staining the hearts with di-4-ANEPPS leads to only short-term sporadic prolongation of impulse conduction through atria and atrioventricular node. On the other hand, significant irreversible slowing of heart rate and ventricular conduction were found in stained hearts as compared to controls. In patch clamp experiments, significant inhibition of sodium current density was observed in differentiated NG108-15 cells stained by the dye. Although no significant differences in mean number of ventricular premature beats were found between the stained and the non-stained hearts in ischemia as well as in reperfusion, all abovementioned results indicate increased arrhythmogenicity. In isolated hearts during ischemia, prominent ischemic patterns appeared in the stained hearts with 3-4 min delay as compared to the non-stained ones. Moreover, the ischemic changes did not achieve the same magnitude as in controls even after 10 min of ischemia. It resulted in poor performance of ischemia detection by proposed EG parameters, as was quantified by receiver operating characteristics analysis. CONCLUSION: Our results demonstrate significant direct irreversible effect of di-4-ANEPPS on spontaneous heart rate and ventricular impulse conduction in rabbit isolated heart model. Particularly, this should be considered when di-4-ANEPPS is used in ischemia studies in rabbit. Delayed attenuated response of such hearts to ischemia might lead to misinterpretation of obtained results.

Doxorubicin and Liposomal Doxorubicin Differentially Affect Expression of miR-208a and let-7g in Rat Ventricles and Atria.

Anthracyclines use is limited by profound cardiotoxicity. Involvement of miRNAs in anthracycline-induced cardiotoxicity (AIC) is still not completely understood. Thus, the expression of AIC-related microRNAs was determined in rat atria and ventricles after doxorubicin (DOX) and liposomal doxorubicin (L-DOX) administration. Vehiculum, DOX or L-DOX were applied intraperitoneally in a single dose to male Wistar rats (3 groups: control, DOX and L-DOX, respectively). Rats were sacrificed after 24 h, and samples from left atrium (LA)/ventricle (LV) and right atrium (RA)/ventricle (RV) were obtained. Expressions of miR-208a, let-7g and snU6 were determined using qRT-PCR. In the control group, miR-208a was highly abundant in the atria compared to the ventricles and in the left-sided structures compared to the right-sided structures, while let-7g showed only atrio-ventricular gradient with predominant expression in the atria. Administration of both DOX and L-DOX resulted in 38.87 and 23.57% reduction in miR-208a expression in the LV (p = 0.028) and in 13.79 and 14.70% reduction in let-7g expression in the LA (p = 0.015), respectively. Acute administration of DOX/L-DOX alters expression of miR-208a in LV and of let-7g in LA. These changes may partly contribute to the development of AIC.

Reduction of Doxorubicin-Induced Cardiotoxicity Using Nanocarriers: A Review.

BACKGROUND: Anthracycline antibiotic doxorubicin (DOX) is a very potent and extensively prescribed chemotherapeutic drug. It is widely utilized in the therapy of variety of haematological and solid tumours, although its administration is commonly accompanied with several severe side effects. The most serious one is a development of dose-dependent and cumulative cardiotoxicity. In the course of time, many strategies have been investigated in order to avoid or at least to diminish DOX-induced cardiac dysfunction; these include reduction of toxic effect by coadministration with iron chelators (dexrazoxane), trastuzumab, taxanes, statins, and ACE-inhibitors. However, the attenuation of cardiotoxic effect is still not satisfactory yet. OBJECTIVE: This review represents an overall appraisal of studies concerning with the utilization of various doxorubicinloaded nanoparticles in the cancer treatment with specific emphasis on those studies evaluating their influence on the reduction of heart tissue damage. CONCLUSION: Introduction of nanoscale drug delivery systems undoubtedly represents nowadays one of the most promising tools for lowering systemic toxicity. Nanoparticles enable to target the therapeutic payload directly towards the tumor tissue, thus leading to the increased accumulation of the drug in the desired tissue and simultaneously protecting surrounding healthy tissues.

Sulforaphane-induced apoptosis involves the type 1 IP3 receptor.

In this study we show that anti-tumor effect of sulforaphane (SFN) is partially realized through the type 1 inositol 1,4,5-trisphosphate receptor (IP3R1). This effect was verified in vitro on three different stable cell lines and also in vivo on the model of nude mice with developed tumors. Early response (6 hours) of A2780 ovarian carcinoma cells to SFN treatment involves generation of mitochondrial ROS and increased transcription of NRF2 and its downstream regulated genes including heme oxygenase 1, NAD(P)H:quinine oxidoreductase 1, and KLF9. Prolonged SFN treatment (24 hours) upregulated expression of NRF2 and IP3R1. SFN induces a time-dependent phosphorylation wave of HSP27. Use of IP3R inhibitor Xestospongin C (Xest) attenuates both SFN-induced apoptosis and the level of NRF2 protein expression. In addition, Xest partially attenuates anti-tumor effect of SFN in vivo. SFN-induced apoptosis is completely inhibited by silencing of IP3R1 gene but only partially blocked by silencing of NRF2; silencing of IP3R2 and IP3R3 had no effect on these cells. Xest inhibitor does not significantly modify SFN-induced increase in the rapid activity of ARE and AP1 responsive elements. We found that Xest effectively reverses the SFN-dependent increase of nuclear content and decrease of reticular calcium content. In addition, immunofluorescent staining with IP3R1 antibody revealed that SFN treatment induces translocation of IP3R1 to the nucleus. Our results clearly show that IP3R1 is involved in SFN-induced apoptosis through the depletion of reticular calcium and modulation of transcription factors through nuclear calcium up-regulation.

Haloperidol cytotoxicity and its relation to oxidative stress.

Haloperidol (HP) is used for the symptomatic treatment of psychosis, manic phases, hyperactivity, aggressiveness, and acute delirium. Long-term use leads to various adverse side effects, especially to severe impairment of extrapyramidal nerve tracts and in particular, altered QT interval and increased incidence of arrhytmias. It is believed that cytotoxicity of HP and its metabolites is responsible for both neurotoxicity and cardiotoxicity. Extrapyramidal and cardiac adverse side effects may be explained by the HP-induced oxidative stress, as implicated by many studies. HP was reported to induce lipid peroxidation with subsequent membrane changes, responsible for cell death. Vice versa, cells resistant to oxidative stress are also resistant to the toxic effects of HP. Similarly, high percentage of patients suffering from extrapyramidal symptoms treated by vitamin E and other lipid-soluble antioxidants demonstrates diminishing of these adverse side effects. HP's ability to induce oxidative stress by multi-modal action (increased metabolism of dopamine, decrease of glutathione content, induction of NF-κB transcription factor, and inhibition of complex I of respiratory chain) has been established just recently. This review brings summarizing view on the cytotoxicity of haloperidol and involvement of reactive oxygen species and oxidative stress HP-induced cytotoxicity.

Determination of oxidative stress and activities of antioxidant enzymes in guinea pigs treated with haloperidol.

Guinea pigs (Cavia porcellus) were treated with haloperidol (HP), and free radical (FR) and ferric reducing antioxidant power (FRAP) assays were used to determine oxidative stress levels. Furthermore, the superoxide dismutase (SOD), glutathione reductase (GR) and glutathione-S-transferase (GST) activity levels were detected and glucose levels and the reduced and oxidized glutathione (GSH/GSSG) ratio were measured in HP-treated and untreated guinea pigs. The present study demonstrated that the administration of HP causes significant oxidative stress in guinea pigs (P=0.022). In animals treated with HP, the activity of GST was significantly increased compared with a placebo (P= 0.007). The elevation of SOD and GR activity levels and increase in the levels of glutathione (GSH) in HP-treated animals were not statistically significant. In the HP-untreated animals, a significant positive correlation was observed between oxidative stress detected by the FR method and GST (r=0.88, P=0.008) and SOD (r=0.86, P= 0.01) activity levels, respectively. A significant negative correlation between the levels of plasma glucose and oxidative stress detected by the FRAP method was observed (r=-0.78, P=0.04). Notably, no significant correlations were observed in the treated animals. In the HP-treated group, two subgroups of animals were identified according to their responses to oxidative stress. The group with higher levels of plasma HP had higher enzyme activity and reactive oxygen species production compared with the group with lower plasma levels of HP. The greatest difference in activity (U/µl) between the two groups of animals was for GR.