Cardiomyopathy development protection after myocardial infarction in rats: Successful competition for major dihydropyridines' common metabolite against captopril.

During the last 25 years angiotensin-converting enzyme inhibitors spectacularly conquered the field of cardiovascular diseases therapy. Nevertheless, lack of new studies concerning side effects associated with their chronic administration seems to be rather confusing. In our previous research, we proved that the main furnidipines' metabolite (M-2) possess multiple cardioprotective actions. Currently, we compared effects of post-infarction long-term oral treatment with M-2 and captopril on hemodynamic parameters and "ischemic cardiomyopathy" development in rats. Myocardial infarction was evoked by permanent left anterior descending coronary artery occlusion for 35 days. Surviving rats were treated with captopril (2 × 25 mg/kg) or M-2 (4 mg/kg) from 6th- 35th day. At 35th day rats' hearts were tested on working heart setup, where following parameters were measured: heart rate, preload pressure, aortic systolic and diastolic pressures, aortic maximum rise and fall, aortic and coronary flow, myocardial oxygen consumption and oximetry in perfusate. Subsequently, heart tissue specimens were assessed during morphological estimation. Captopril caused significant heart rate increase and markedly diminished preload pressure in comparison to M-2. Both drugs evoked essential aortic pressure increase. Aortic flow was significantly decreased after M-2, whereas captopril increased this parameter in comparison to M-2. Both agents caused marked coronary flow increase. Morphologic examination in captopril revealed cardiomyopathic process in 70% of hearts, whereas in M-2 this value reached 30%. Neovascularization of post-infarcted myocardium was visible only after M-2 therapy. Concluding, M-2 presented itself as more attractive agent in long-term post-infarction treatment by preventing cardiomyopathy development, angiogenesis stimulation and preserving cardiac performance.

New approach to molsidomine active metabolites coming from the results of 2 models of experimental cardiology.

Molsidomine is a well-known vasodilatating, antianginal drug. Despite earlier studies with its metabolites (3-morpholino-syndnonimine (SIN-1) and N-nitroso-N-morpholino-amino-acetonitrile (SIN-1A)), which indicated a potential favorable cardioprotective activity, a lot of controversy remains. The aim of our research was to compare molsidomine, SIN-1, SIN-1A, and lidocaine influence on arrhythmias and hemodynamic parameters in 2 experimental models in rats. In the Langendorff heart study, SIN-1A markedly elevated left ventricular systolic pressure, maximum rise and fall of the first pressure derivative, coronary flow, and myocardial oxygen consumption. In addition, SIN-1A more so than SIN-1 significantly lowered creatine kinase release. The antiarrhythmic action of SIN-1 was observed, while lidocaine significantly diminished ventricular arrhythmias duration in comparison with the control. In the ischemia-reperfusion-induced arrhythmias model, hypotensive action of molsidomine was observed as well as the reduction in pressure rate product. Molsidomine also prolonged ventricular tachycardia duration. On the other hand, no significant effects on hemodynamic parameters as well as on ventricular arrhythmias were found in any of the SIN-1 and SIN-1A groups. In conclusion, our research suggests a possible direct, cardioprotective action of SIN-1A. It seems worthwhile to further investigate molsidomine derivatives, especially SIN-1A, because of its potential use in invasive cardiology procedures such as percutaneous transluminal coronary angioplasty.

Prognostic value of collagen turnover biomarkers in cardiac resynchronization therapy: A subanalysis of the TRUST CRT randomized trial population.

BACKGROUND: A substantial proportion of patients do not respond to cardiac resynchronization therapy (CRT). Various echocardiographic and biochemical markers including collagen turnover biomarkers were suggested to predict CRT results. However, pathological significance of collagen turnover biomarkers in CRT remains controversial. OBJECTIVE: The aim of the present study was to evaluate the relationship between levels of collagen turnover biomarkers (amino-terminal propeptide of procollagen type I and amino-terminal propeptide of procollagen type III [PIIINP]), N-terminal of the prohormone brain natriuretic peptide (NT-proBNP), high-sensitivity C-reactive protein, and matrix metalloproteinases (metalloproteinase-2 and metalloproteinase-9) and echocardiographic response to CRT and clinical outcomes. METHODS: The study population consisted of patients enrolled in the Triple Site Versus Standard Cardiac Resynchronization Therapy trial. Blood samples were obtained before implantation of a CRT with defibrillator. The levels of PIIINP, amino-terminal propeptide of procollagen type I, metalloproteinase-2, and metalloproteinase-9 were determined using commercially available ELISA kits. High-sensitivity C-reactive protein and NT-proBNP levels were determined in a standard way. RESULTS: Samples were collected from 74 of 100 enrolled patients. The multivariate logistic regression analysis demonstrated that low PIIINP levels (odds ratio [OR] 3.56; 95% confidence interval [CI] 1.23-10.24; P = .017) and baseline ejection fraction (OR 2.14; 95% CI 1.11-4.11; P = .02) were favorably associated with echocardiographic response. PIIINP and NT-proBNP levels appeared to be independent predictors of all-cause mortality (PIIINP: OR 3.11; 95% CI 1.21-7.89; P = .033; NT-proBNP: OR 2.05; 95% CI 1.11-4.96; P = .039) and risk of major cardiac adverse event (PIIINP: OR 3.56; 95% CI 1.53-9.15; P = .007; NT-proBNP: OR 4.51; 95% CI 1.75-11.6; P = .001). PIIINP levels showed significant additive value in predicting mortality as compared with NT-proBNP levels, but they were not superior to ejection fraction in predicting response. Survival analysis with cutoff values identified by receiver operating characteristic analysis confirmed a significant benefit associated with low baseline PIIINP levels. CONCLUSION: Low PIIINP levels are associated with favorable echocardiographic response and long-term survival in CRT recipients.

Dihydropyridines' metabolites-induced early apoptosis after myocardial infarction in rats; new outlook on preclinical study with M-2 and M-3.

Our previous studies established cardio-protective effects of furnidipine and its active metabolites called M-2 and M-3. The aim of current research was to compare the effects of single oral pretreatment with 20 mg kg(-1) of M-2 and M-3 on mortality, different forms of arrhythmias, blood pressures parameters and ST-segment changes during occlusion (for 90 min) and reperfusion in the model of myocardial infarction in rats evoked by left anterior descending coronary artery occlusion. Additionally, the development of programmed cell death and biochemical parameters in blood serum were studied at 4th day after infarction. Furnidipines' metabolites effectively reduced mortality index while did not markedly influence on blood pressures parameters, arrhythmias, ST-segment changes as well as biochemical parameters. Intriguingly, programmed cell death study (TUNEL) showed distinct increase in the amount of apoptotic nuclei in post-infarcted myocardium, granulation tissue and what is more in arteriolar walls after M-2 and M-3 application. Moreover, M-2 turned out to be more powerful in stimulation of apoptosis in granulation tissue surrounding infarcted area whereas M-3 presented balanced profile in this matter. Taking into account that programmed cell death plays positive role in post-infarcted heart healing, M-2 presents itself as more attractive agent for oral pretreatment in early stages of ischemia by non-stable individuals due to its more specific action in stimulation repairing processes in granulation tissue as well as in arteriolar walls. While M-2 and M-3 are common metabolites present in degradation pathways of many widely used dihydropyridines in clinic, this key fact put the new outlook on understanding additional mechanism and effects of not only furnidipines' metabolites but also other dihydropyridines.

Differential effects of furnidipines' metabolites on reperfusion-induced arrhythmias in rats in vivo.

We previously established that furnidipine (FUR) and oxy dihydropyridines prevent rats mortality by strong reduction of the lethal arrhythmias in reperfusion. Therefore we decided to study the influence of three main metabolites (M-2, M-3, M-8) of FUR on ischemia-and reperfusion- induced arrhythmias and hemodynamic parameters in rat model to examine their independent activity. The metabolites (M-2, M-3, M-8) were given orally 20 mg/kg (24 and 1 h before ischemia). Mortality was significantly diminished in M-2 and M-3 treated groups with M-3 preventing animal mortality entirely. All three examined substances significantly reduced the duration and incidence of ventricular fibrillation (VF) with M-3, once again, completely preventing VF. Moreover, only M-3 significantly decreased the duration of ventricular tachycardia but had no influence on their incidence. Through the occlusion and reperfusion periods, M-2 and M-3 were markedly less hypotensive than M-8 and did not influence on heart rate. We conclude that two tested metabolites of FUR, M-3 and M-2 exhibited the most pronounced anti-arrhythmic effect being at the same time the most normotensive and therefore caused the most beneficial effects.

Anti-arrhythmic and hemodynamic effects of oxy nifedipine, oxy nimodipine, oxy nitrendipine and oxy nisoldipine.

Our previous studies have established cardio-protective effects of furnidipine and its active metabolites. We therefore decided to compare the influence of oral and intravenous administration of furnidipine, nifedipine, nitrendipine and nimodipine to examine their effects on hemodynamics and arrhythmias. Since dihydropyridines are oxidatively metabolized in the body and the oxidized metabolites are among the final products, we studied the influence of four oxidized dihydropyridines (oxy nifedipine, oxy nimodipine, oxy nitrendipine and oxy nisoldipine) on the same parameters. In vivo model of ischemia- and reperfusion-induced arrhythmias of rats was used. Dihydropyridines were administered 5 mg/kg orally (24 and 1 h before ischemia) or 5 µg/kg intravenously (10 min before ischemia). 20 mg/kg of the oxidized dihydropyridines was given orally (24 and 1 h before ischemia). The dihydropyridines exhibited significant anti-arrhythmic actions after both forms of administration but their influence on blood pressure was differential and contrasting and depended on route of administration. The oxidized dihydropyridines imparted strong protection against lethal arrhythmias while exerting differential influences on blood pressure with oxy nifedipine and oxy nisoldipine being hypertensive and oxy nitrendipine being most normotensive. The differential effects observed with the dihydropyridines after the two routes of administration lend strength to the hypothesis that their metabolites may have a significant role in mediating the actions of the parent drug. The strong anti-arrhythmic action of the oxidized dihydropyridines along with their differential effect on blood pressure could indicate their potential use as cardio-protective drugs in certain groups of patients.

[Derivatives of 1,4-dihydropyridines as "priviledged structures" and their pharmacological potential]. / Pochodne 1,4-dihydropirydyny jako "struktury uprzywilejowane" i ich potencjal farmakologiczny.

Derivatives of 1,4-dihydropyridine belong to group of calcium channel blockers and remain large group of antihypertensive agents. Particular chemical structure and presence of highly reactive binding groups make 1,4-dihydropyridines "privileged structures", which can be modified and change their pharmacological effects. This fact applies to new derivatives as well as metabolites of those drugs. Particularly interesting are outcomes of experiments with metabolites of furnidypine, which tend to cause different pharmacological effect, as well as have different profile of adverse effects from mother drug. Our paper concerns with potential new possibilities of using derivatives of 1,4-dihydropyridines, as well as their metabolites, as agents of more "optimised" effect.

Beneficial effects of l-leucine and l-valine on arrhythmias, hemodynamics and myocardial morphology in rats.

Branched chain amino acids (BCAA) have been shown to have a general protective effect on the heart in different animal models as well as in humans. However, so far no attempt has been made to specifically elucidate their influence on arrhythmias. Our study was performed to evaluate whether an infusion of either l-leucine or l-valine in a dose of 1mgkg(-1)h(-1) 10min before a 7-min period of left anterior descending artery occlusion followed by 15min of reperfusion, had an effect on arrhythmias measured during the reperfusion phase in the ischemia- and reperfusion-induced arrhythmias model in rats in vivo. The effect of the infusion of these substances on mean arterial blood pressure was monitored throughout the experiment. Both of the tested amino acids exhibited significant antiarrhythmic properties. l-Leucine reduced the duration of ventricular fibrillation (P<0.05) and l-valine decreased the duration of ventricular fibrillation (P<0.001) and ventricular tachycardia (P<0.05). The two amino acids were generally hypotensive. l-Valine lowered blood pressure in all phases of the experiment (P<0.05) while l-leucine lowered this parameter mainly towards the end of occlusion and reperfusion (P<0.05). In addition, 30min infusion of the amino acids in the used dose did not produce any apparent adverse histological changes that were remarkably different from control. In summary, the results of our study suggest that l-leucine and l-valine in the dose that was used attenuates arrhythmias and are hypotensive in their influence. Our findings lend support to the many ongoing investigations into the benefit of the application of l-leucine and l-valine in cardiology like their addition to cardioplegic solutions.

Cardioprotective effects of an active metabolite of furnidipine in 2 models of isolated heart and on in vivo ischemia­induced and reperfusion-induced arrhythmias in rats.

Dihydropyridines are known not only to have antiarrhythmic effects but also to exert a significant cardiac depressive influence. We previously showed that M-2, an active and final metabolite of furnidipine, had cardioprotective effects without the marked cardiac depression seen with this dihydropyridine. We studied the influence of M-2 infusion (10(-7) M) on hemodynamics during low-flow and regional ischemia in the rat working heart. We examined the protection conferred by M-2 infusion (10(-7) M) against effects of veratridine-induced intracellular calcium overload in the Langendorff heart. Additionally, we performed an in vivo study to explore the effects of oral administration of M-2 at different times and doses, in the ischemia- and reperfusion-induced arrhythmias model. M-2 improved coronary flow during low-flow and regional ischemia while favorably maintaining aortic pressure parameters. M-2 provided outstanding protection against deleterious effects of calcium overloading by significantly preventing rise in left ventricular diastolic pressure and decrease in coronary flow. M-2 reduced mortality and incidence and duration of severe arrhythmias while exhibiting differential influence on blood pressure, which depended on dose and time of administration and could suggest its clinical indication. The results of our entire study establish a beneficial cardioprotective role of M-2, which exhibited pleiotropic effects on the ischemic heart by imparting protection in various ways. This combined with good tolerance, long duration of action, low toxicity, and relatively large therapeutic window makes M-2 a promising candidate as a precursor for a new chemical class of cardioprotective drugs.

Differential effects of four xylidine derivatives in the model of ischemia- and re-perfusion-induced arrhythmias in rats in vivo.

The aim of our study was to find the most effective xylidine derivative, which reduced mortality, reduced incidence and duration of severe arrhythmias and had a beneficial influence on hemodynamic parameters in an in vivo setting. We compared the action of lidocaine, articaine, ropivacaine and mepivacaine in a dose 2.5 or 5mg/kg/ml/h infused from 10min before left anterior descending coronary artery occlusion until the end of the experiment. In the rat ischemia- and re-perfusion-induced arrhythmia models, the following parameters were measured or calculated: mortality index, ventricular fibrillation and tachycardia incidence and duration, systolic, diastolic and mean arterial blood pressure, heart rate and pressure rate product. Lidocaine produced the most significant reduction in mortality index (P<0.05) after both doses. At the higher dose, lidocaine and articaine shortened ventricular fibrillation and tachycardia duration (P<0.05-P<0.001), while ropivacaine prolonged them. A hypertensive effect was observed after a lower dose of lidocaine during occlusion and early re-perfusion as compared to others (P<0.05). Beneficial effects were mainly observed with lidocaine, which protected against sudden cardiac death. The novelty was lidocaine's dose independent protection against blood pressure drop in early re-perfusion, which could be linked to the effects observed on the other end-points. Articaine showed beneficial effects but they weren't as pronounced as that of lidocaine. Nevertheless, in the light of our results, articaine could supposedly be used as a substitute for lidocaine in patients with hypertension.

Comparison of thiopental, urethane, and pentobarbital in the study of experimental cardiology in rats in vivo.

BACKGROUND: Despite earlier research studying the influence of anesthetics in arrhythmia models, a lot of controversy remains. The aim was to compare the influence of three anesthetics (60 mg/kg thiopental, 1200 mg/kg urethane, 60 mg/kg pentobarbital intraperitoneally) on ventricular arrhythmias and to combine it with measured hemodynamic parameters to find the most suitable agent for such experiments. METHOD: In the model of ischemia- and reperfusion-induced arrhythmias in Sprague-Dawley rats, after left anterior descending coronary artery occlusion (7 minutes) and reperfusion (15 minutes), the following parameters have been measured or calculated: mortality index; ventricular fibrillation and tachycardia incidence and duration; systolic, diastolic, and mean arterial blood pressure; heart rate; myocardial index of oxygen consumption; and plasma creatine kinase concentration. RESULTS: Evident depressive action of urethane on heart rate, blood pressures, and myocardial index of oxygen consumption should be reason enough to exclude it from use in such studies. Pentobarbital had no effect on arrhythmias, whereas thiopental was antiarrhythmic. CONCLUSIONS: Pentobarbital is the most suitable anesthetic offering stable hemodynamic values during arrhythmia studies. These hemodynamic values, which were similar to physiological values in awake rats, the long arrhythmia duration during reperfusion and approximately 50% mortality index are crucial parameters for evaluating antiarrhythmic drugs.

Determination of selected beta-receptor antagonists in biological samples by solid-phase extraction with cholesterolic phase and LC/MS.

A new method is presented for the determination of five selected beta-receptor antagonists by HPLC, which emphasizes sample preparation via retention on a new type of silica gel sorbent used for solid-phase extraction (SPE). Sorbents of this type were obtained by the chemical modification of silica gels of various porosities by cholesterol ligands. The cholesterol-based packing material was investigated by spectroscopic methods and elemental analysis. The recoveries obtained with the extraction procedure were optimum over a relatively broad sample pH range (3.08-7.50). Analytical factors such as the sample loading, the washing step and elution conditions, the concentration of beta-receptor antagonists to be extracted, and the type of sorbent were found to play significant roles in the sample preparation procedure and would therefore need to be controlled to achieve optimum recoveries of the analytes. Under optimum conditions, the recoveries of nadolol, acebutolol, esmolol, oxprenolol and propranolol from spiked buffers, blood and urine were reproducible and dependent on the polarity or hydrophilicity of the compounds. The above analytes were determined by reverse-phase high-performance liquid chromatography (HPLC) with UV and ESI-ion trap mass spectrometry (MS) detection. The described method was found to be suitable for the routine measurement of compounds that are both polar and basic, and can be applied for the analysis of biological samples such as urine and blood in clinical, toxicological or forensic laboratories. The recovery measurements were performed on spiked human urine and serum, and on real samples of mouse blood serum.

Differential effects of furnidipine and its active metabolites in rat isolated working heart.

1,4,-dihydropyridines, belonging to the class of "privileged structures", are known to protect the heart from stunning, ischemia and ventricular arrhythmias and mainly used in hypertension. The aim of this study was to compare the continuous infusion of parent drug, furnidipine, with its two active metabolites (M-2; M-3) in rat isolated working heart model, where the following parameters were measured and calculated: heart rate, preload pressure, aortic systolic and diastolic pressures (AoD), as well as +/-dP/dt, aortic (AF) and coronary flow (CF), oxygen and carbon dioxide partial pressures and pH values in pulmonary effluent, myocardial oxygen consumption. At first, the optimal vasodilatatory dose of M-2 was estimated and afterwards it was compared with equivalent doses of both remaining substances. The strongest vasodilatatory effects were observed after the lowest dose of M-2 was used (10(-7) M), at the same time being without marked influence on pressure parameters. The pro-drug evoked significantly weaker influence on both flows. Furthermore, furnidipine significantly reduced AoD and AF in comparison to control as well as +dP/dt in comparison to the initial values, while M-2 did not. Both metabolites caused a significant CF increase, but M-3 additionally the AoS and AoD decrease in comparison to the control. Regarding clear differences in the measured parameters between the pro-drug and its metabolites found, the obtained results allow to claim that the metabolites vs. furnidipine possess a beneficial influence. The distinct flow shift from aorta into the coronaries was observed only after M-2 and to a lesser extent--M-3. The cardio-depressant potency of both metabolites is overcome by advantageous vasodilatatory effect. M-2, being a final product, easier to control and at the same time a precursor of the new chemical class of therapeutics, is promising as a cardio-protective agent.

Wide-spread myocardial remodeling after acute myocardial infarction in rat. Features for heart failure progression.

The aim of the present study was to assess the relationship between hemodynamic function and cardiac remodeling post-myocardial infarction (MI) in Sprague-Dawley rats - the most commonly used species in pre-clinical studies. The experimental MI was induced by left coronary artery occlusion and the hemodynamics (working heart set-up) were measured at 2, 4, 6, 11, 21, 28, 35 or 70 days as well as morphological features. The maximal increase of coronary and aortic flow (CF, AF), the aortic systolic pressure (AoS) and contraction (+dP/dt; -dP/dt) values were observed at day 4 in comparison to sham-operated rats. By contrast, the preload pressure and aortic diastolic pressure (PP, AoD) were significantly decreased. These drastic changes were followed by recent cardiomyocyte necrosis, hyperemic capillaries and proliferating young vessels. At day 6, a deep drop down of AoS, +dP/dt, -dP/dt and CF was noted, while AF, AoD and PP approximated to the sham values. The recovery was reached in the case of AoS, -dP/dt and AF at day 28, +dP/dt did not recover till day 70, while CF was markedly increased. Accordingly, the inflammatory infiltration was diminished, connective tissue and collagenized scar with a number of capillaries was observed. The recent cardiomyopathy was observed at day 28 and fixed at day 35 with significant decline of AoS, AoD and CF. Clearly, the all natural post-MI compensatory mechanisms (remodeling) were exhausted between 28 and 35 days, while most of the parameters remained unchanged up to 70 days. These changes showed nonlinear, three-phase development of the post-MI heart function in non-treated rat (I, up to 4; II, 6-28; III, 70 days). The morphological processes correlated hemodynamically, however, they were slightly delayed. This model could be fast and relevant in pre-clinical study.

Anti-arrhythmic and cardio-protective effects of furnidipine in a rat model: a dose response study.

Protective effects of acute oral or intravenous doses of furnidipine against ischemia and re-perfusion-induced arrhythmias and creatine kinase release were studied in a rat model for cardiac ischemia and re-perfusion. Transient cardiac ischemia was induced by occluding the left coronary descending artery of anaesthetized rats for 7 min, and re-perfusion period studied was 15 min. Pre-treatment period for oral doses (1, 5 or 10 mg/kg) was 1 h, whereas that for the intravenous ones (1.25, 2.5, 5 or 10 microg/kg) was 10 min. After both routes of administration, significant protective effects of furnidipine on creatine kinase release were observed after the two lowest doses only. In contrast, its higher dosages were more effective in preventing re-perfusion-induced mortality, arrhythmias and hypotensive episodes, and for transiently lowering arterial blood pressure before initiation of ischemia. These observations suggest potential uses of furnidipine for preventing re-perfusion triggered lethal arrhythmias. Efforts to evaluate therapeutic potential of low dose furnidipine as a cardio-protective agent seem warrantable.

Angiogenesis and cardioprotection after TNFalpha-inducer-Tolpa Peat Preparation treatment in rat's hearts after experimental myocardial infarction in vivo.

The aim of the presented work was to evaluate whether short subcutaneous (s.c.) administration of TNFalpha-inducer-Tolpa Peat Preparation (TPP or TPP batch 0210) modulates the process of ischemic remodeling and spontaneous angiogenesis after experimental myocardial infarction (MI) in rats in vivo. The results obtained using three complementary and correlative methods: histological studies, Proliferating Cell Nuclear Antigen (PCNA) reaction and Lymphocytes Induced Angiogenesis (LIA) test showed a clear pro-angiogenic and cardioprotective effect of TPP administration after experimental MI. TPP batch 0210 should be considered as an angiogenesis stimulating factor and consecutively as a cardioprotective preventing development of ischemic cardiomyopathy after MI in rats. It might possibly be used as an adjunct to conventional therapy of coronary artery disease, including late phase after myocardial infarction or ischemic cardiomyopathy.