The perfusion of cisplatin and cisplatin structural analogues through the isolated rat heart: The effects on coronary flow and cardiodynamic parameters.

The therapeutic use of cisplatin for the treatment of solid tumours is associated with organ toxicity. Amongst those, the cardiotoxicity is an occasional but very serious and severe side effect. To prevent or reduce these negative effects, many cisplatin analogues have been synthesized and evaluated in terms of being a less toxic and more effective agent. In present study, we examined the effects of cisplatin and its three analogues in the isolated rat heart to determine whether changes in the structure of the platinum complexes (changing of carrier ligands - ethylenediamine; 1,2-diaminocyclohexane; 2,2':6',2''-terpyridine) can influence their cardiotoxic effects. The results of our research indicate that the introduction of aromatic rings in the structure of the platinum complexes has a negative influence on the heart function. Conversely, the other two examined complexes had less negative effects on heart function compared to cisplatin. Our findings may be of interest for a possible synthetic strategy of introducing a carrier ligand that will exert a less cardiotoxic effect.

Comparison of training and detraining on redox state of rats: gender specific differences.

Given the fact that oxidative stress response induced by training/detraining has still not been clarified and may be influenced by gender, the aim of our investigation was to compare the effects of swimming training and detraining on oxidative and antioxidative parameters in rats, with a special focus on sex differences. Wistar albino rats (n = 64) were divided into 4 groups: control, trained group, groups exposed to 2 and 4 weeks of detraining. Each group included two subgroups: males and females. After sacrificing, hearts were isolated and retrogradely perfused according to Langendorff technique. Levels of superoxide anion radical, hydrogen peroxide, nitrites and thiobarbituric acid reactive substances were measured in plasma and coronary venous effluent, while reduced glutathione, activities of superoxide dismutase and catalase were measured in erythrocytes. Our results indicate that swimming training doesn't promote oxidative damage, nor act protectively within the heart. However, 2 and 4 weeks of detraining led to a partial lost in exercise-induced adaptation. It seems that moderate-intensity physical exercise of sufficient duration leads to beneficial adaptations, which may be partially lost during detraining period. Positive antioxidative effects of training remained longer in males. Findings of present study may help in elucidation of training and detraining effects on modulation of redox homeostasis, especially from aspect of gender differences.

Cisplatin and cisplatin analogues perfusion through isolated rat heart: the effects of acute application on oxidative stress biomarkers.

Drug-induced oxidative stress can occur in numerous tissues and organ systems (liver, kidney, ear, nervous system, and cardiovascular system). Cancer therapy with cisplatin is associated with side effects to which oxidative stress may contribute. We have compared the influences of cisplatin (reference compound) and its' analogues (dichloro(1,2-diaminocyclohexane)platinum(II) and chloro(2,2':6',2″-terpyridine)platinum(II)) in a model of isolated rat heart using the Langendorff technique. The production of oxidative stress biomarkers, antioxidant enzymes, myocardial damage, and expression of Bax, OH-1, and SODs were studied. Cisplatin and the analogues were perfused at concentration of 10-6 and 10-5 M during 30 min. The results of this study showed that examined platinum complexes had different ability to induce oxidative stress of isolated perfused rat heart. Varying the carrier ligands, such as 1,2-diaminocyclohexane and 2,2':6',2″-terpyridine, related to amino ligands (cisplatin) directly influenced the strength to induce production of oxidative stress biomarkers. Introducing 2,2':6',2″-terpyridine ligands provoked the smallest changes in antioxidant enzymes activity, lipid peroxidation, and expression of heme oxygenase-1, that undoubtedly indicated that this complex had the lowest impact on redox status in heart tissue. These findings may be useful in synthesis of novel platinum analogues with lower potential for oxidative stress induction. However, the fact that platinum complexes could induce toxic effects in the heart by other mechanisms should be taken into the consideration.

Estradiol decreases blood pressure in association with redox regulation in preeclampsia.

In this study, we tested a hypothesis that a short-term estradiol therapy may reduce blood pressure in preeclampsia by modulating plasma oxidative stress. The intramuscular injections of 10 mg 17-beta-estradiol were prescribed to preeclamptic pregnant women during the 3-day therapy before a labor induction. The analyses of mean arterial pressure (MAP), serum estradiol concentrations, plasma superoxide anion (O2.), hydrogen peroxide (H2O2), nitrites (NO2-), and peroxynitrite (ONOO-) were conducted before and during the therapy. We found that the plasma concentrations of oxidative stress markers, such as O2- and H2O2, are higher in preeclampsia and positively correlated with the MAP value. Moreover, it was shown that the plasma concentration of NO2- as an indicator of NO levels is higher in preeclampsia. A short-term intramuscular application of estradiol decreases the MAP value and the plasma concentration of O.-, H2O2, NO2-, and ONOO- in preeclampsia. A positive correlation between the decrease of MAP values and the decrease of plasma concentrations of O2-, H2O2, and ONOO- was found in preeclampsia during a short-term estradiol therapy. We conclude that the short-term estradiol therapy decreases the MAP value in preeclampsia by modulating the plasma oxidative stress. We speculate that the estradiol metabolism in preeclampsia is an important mechanism that contributes to vascular dysfunction.

Modulation of N-methyl-d-aspartate receptors in isolated rat heart.

Considering the limited data on the role of NMDA-Rs in the cardiovascular system, the aim of the present study was to examine the effects of NMDA and DL-Hcy TLHC, alone and in combination with glycine, memantine, and ifenprodil, in the isolated rat heart. The hearts of Wistar albino rats were retrogradely perfused according to the Langendorff technique at a constant perfusion pressure. The experimental protocol for all experimental groups included the stabilization period, application of estimated substance for 5 min, followed by a washout period of 10 min. Using a sensor placed in the left ventricle, we registered the following parameters of myocardial function: dp/dtmax, dp/dtmin, SLVP, DVLP, HR; CF was measured using flowmetry). We estimated the following oxidative stress biomarkers in the coronary venous effluent using spectrophotometry: TBARS, NO2-, O2-, and H2O2. NMDA alone did not induce any change in any of the observed parameters, while DL-Hcy TLHC alone, as well as a combined application of NMDA and DL-Hcy TLHC with glycine, induced a reduction of most cardiodynamic parameters. Memantine and ifenprodil induced a reduction of cardiodynamic parameters and CF, as well as some oxidative stress biomarkers.

The acute effects of different spironolactone doses on cardiac function in streptozotocin-induced diabetic rats.

Currently, cardiovascular diseases are the leading cause of global mortality, while diabetes mellitus remains an important cause of cardiovascular morbidity. A recent study showed that patients with diabetes mellitus treated with mineralocorticoid receptor antagonists have improved coronary microvascular function, leading to improved diastolic dysfunction. In this study, we evaluated the influence of acute administration of spironolactone on myocardial function in rats with streptozotocin-induced diabetes mellitus, with special emphasis on cardiodynamic parameters in diabetic rat hearts. The present study was carried out on 40 adult male Wistar albino rats (8 weeks old). Rats were randomly divided into 4 groups (10 animals per group): healthy rats treated with 0.1 µmol/L of spironolactone, diabetic rats treated with 0.1 µmol/L of spironolactone, healthy rats treated with 3 µmol/L of spironolactone, and diabetic rats treated with 3 µmol/L of spironolactone. Different, dose-dependent, acute responses of spironolactone treatment on isolated, working diabetic and healthy rat heart were observed in our study. In healthy rats, better systolic function was achieved with higher spironolactone dose, while in diabetic rats, similar effects of low and high spironolactone dose were observed.

The effects of verapamil and its combinations with glutamate and glycine on cardiodynamics, coronary flow and oxidative stress in isolated rat heart

The role of N-methyl-D-aspartate receptor (NMDA-R) in heart is still unclear. For these ionotropic glutamate receptors is characteristic the necessity of both co-agonists, glutamate and glycine, for their activation, which primarily allows influx of calcium. The aim of the present study was to examine the effects of verapamil, as a calcium channel blocker, alone and its combination with glycine and/or glutamate on cardiac function, coronary flow, and oxidative stress in isolated rat heart or to examine the effects of potential activation of NMDA-R in isolated rat heart. The hearts of male Wistar albino rats were excised and perfused according to Langendorff technique, and cardiodynamic parameters and coronary flow were determined during the administration of verapamil and its combinations with glutamate and/or glycine. The oxidative stress biomarkers, including thiobarbituric acid-reactive substances, nitrites, superoxide anion radical, and hydrogen peroxide, were each determined spectrophotometrically from coronary venous effluent. The greatest decline in parameters of cardiac contractility and systolic pressure was in the group that was treated with verapamil only, while minimal changes were observed in group treated with all three tested substances. Also, the largest changes in coronary flow were in the group treated only with verapamil, and at least in the group that received all three tested substances, as well as the largest increase in oxidative stress parameters. Based on the obtained results, it can be concluded that NMDA-R activation allows sufficient influx of calcium to increase myocardial contractility and systolic pressure, as well as short-term increase of oxidative stress (AU)

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The effects of verapamil and its combinations with glutamate and glycine on cardiodynamics, coronary flow and oxidative stress in isolated rat heart.

The role of N-methyl-D-aspartate receptor (NMDA-R) in heart is still unclear. For these ionotropic glutamate receptors is characteristic the necessity of both co-agonists, glutamate and glycine, for their activation, which primarily allows influx of calcium. The aim of the present study was to examine the effects of verapamil, as a calcium channel blocker, alone and its combination with glycine and/or glutamate on cardiac function, coronary flow, and oxidative stress in isolated rat heart or to examine the effects of potential activation of NMDA-R in isolated rat heart. The hearts of male Wistar albino rats were excised and perfused according to Langendorff technique, and cardiodynamic parameters and coronary flow were determined during the administration of verapamil and its combinations with glutamate and/or glycine. The oxidative stress biomarkers, including thiobarbituric acid-reactive substances, nitrites, superoxide anion radical, and hydrogen peroxide, were each determined spectrophotometrically from coronary venous effluent. The greatest decline in parameters of cardiac contractility and systolic pressure was in the group that was treated with verapamil only, while minimal changes were observed in group treated with all three tested substances. Also, the largest changes in coronary flow were in the group treated only with verapamil, and at least in the group that received all three tested substances, as well as the largest increase in oxidative stress parameters. Based on the obtained results, it can be concluded that NMDA-R activation allows sufficient influx of calcium to increase myocardial contractility and systolic pressure, as well as short-term increase of oxidative stress.

The effects of zofenopril on cardiac function and pro-oxidative parameters in the streptozotocin-induced diabetic rat heart.

Diabetes mellitus is a chronic condition that continues to increase in both incidence and prevalence. Renin-Angiotensin-Aldosterone System is one of the main modulators of chronic hyperglycaemia and, thus, its influence on tissues. Hyperglycaemia-induced oxidative stress is an important factor in diabetic cardiomyopathy. The present study was carried out on 24 adult male Wistar albino rats (8-week-old and with body masses of 190 ± 10 g). We evaluated the influence of acute administration of zofenopril on ex vivo myocardial function from rats with streptozotocin-induced diabetes mellitus, with a special emphasis on cardiodynamic and oxidative stress parameters in diabetic rat hearts. Rats were divided randomly into two groups (12 animals per group): control non-diabetic animals (C) were healthy rats perfused with 1.5 µM of zofenopril, and STZ-treated diabetic animals (DM) were diabetic animals perfused with 1.5 µM of zofenopril 4 weeks after the induction of diabetes. Our results demonstrated that diabetic rats are characterized by a depressed cardiac performance and that oxidative markers are related to alterations in cardiac function in rats with 4 weeks of STZ-induced diabetes. Additionally, the use of zofenopril as a monotherapy slightly diminished cardiac damage induced by chronic hyperglycaemia. However, long-term follow-up intervention trials are necessary to fully demonstrate the benefit of zofenopril in this context. A challenge for future investigations will be to identify the effects of chronic administration or combination therapy with angiotensin-converting enzyme inhibitors in various models of diabetes.

Angiotensin Receptor Blocker Losartan Inhibits Spontaneous Motility of Isolated Human Ureter.

BACKGROUND AND OBJECTIVES: Ureteral motility is essential for elimination of intraluminal stones, and it may be adversely affected by cardiovascular drugs that a patient is taking chronically. The aim of our study was to test whether ACE inhibitors and an angiotensin receptor blocker may influence spontaneous contractions of isolated human ureter. METHODS: Both phasic and tonic contractions of the isolated ureteral segments taken from 10 patients were measured as changes of the longitudinal tension or pressure recordings. Captopril, enalapril and losartan were separately added to the organ baths cumulatively. RESULTS: While enalapril (2.7 × 10-7-3.9 × 10-4 M) and captopril (6.1 × 10-7-2.7 × 10-3 M) did not affect either spontaneous activity or tone of isolated ureteral segments, losartan (2.9 × 10-7-4.2 × 10-4 M) caused concentration-dependent inhibition of spontaneous contractions of the segments (50 % effective concentration (EC50) = 13.46 ± 1.80 × 10-6 M; F = 10.72, r = 0.79, p < 0.001). CONCLUSIONS: Due to differences in molecular mechanism of action, angiotensin receptor blocker losartan does and ACE inhibitors captopril and enalapril do not inhibit spontaneous contractions of isolated human ureter.

Calcitonin Gene-Related Peptide Receptor Blocker Inhibits Spontaneous Activity of Human Ureter.

Calcitonin gene-related peptide (CGRP) is present in nerve fibers that innervate the human ureter and may have important influence on the motility of this organ. The aim of our study was to investigate whether CGRP could affect the motility of an isolated human ureter. The tension and intraluminal pressure of the isolated ureteral segments were recorded and registered on a personal computer. Both phasic and tonic contractions of the isolated preparations were measured as area under the tension or pressure recordings. CGRP and CGRP fragment 8-37 were separately added to the organ baths in a cumulative way, thereby gradually increasing their concentration in the baths' solution. Alpha-CGRP did not affect either phasic, spontaneous activity or tone of isolated ureteral segments, as measured by both tension and intraluminal pressure. On the other hand, CGRP 8-37 caused concentration-dependent inhibition of spontaneous contractions of the isolated ureteral segments.