[Birth and separation, questioning caesarean deliveries on maternal request]. / Naissance et séparation, interroger les césariennes sur demande maternelle.

Clinical practice and literature highlight the emergence and the growth in the number of caesareans carried out on the request of the mother without medical indication. For some women, a vaginal delivery is an anachronism, while for others it is a necessary passage towards motherhood. A reflection was carried out to illustrate the singularity behind these requests and attempt to overcome the 'for' and 'against' divide.

Role of SOCS2 in modulating heart damage and function in a murine model of acute Chagas disease.

Infection with Trypanosoma cruzi induces inflammation, which limits parasite proliferation but may result in chagasic heart disease. Suppressor of cytokine signaling 2 (SOCS2) is a regulator of immune responses and may therefore participate in the pathogenesis of T. cruzi infection. SOCS2 is expressed during T. cruzi infection, and its expression is partially reduced in infected 5-lipoxygenase-deficient [knockout (KO)] mice. In SOCS2 KO mice, there was a reduction in both parasitemia and the expression of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), IL-6, IL-10, SOCS1, and SOCS3 in the spleen. Expression of IFN-γ, TNF-α, SOCS1, and SOCS3 was also reduced in the hearts of infected SOCS2 KO mice. There was an increase in the generation and expansion of T regulatory (Treg) cells and a decrease in the number of memory cells in T. cruzi-infected SOCS2 KO mice. Levels of lipoxinA(4) (LXA(4)) increased in these mice. Echocardiography studies demonstrated an impairment of cardiac function in T. cruzi-infected SOCS2 KO mice. There were also changes in calcium handling and in action potential waveforms, and reduced outward potassium currents in isolated cardiac myocytes. Our data suggest that reductions of inflammation and parasitemia in infected SOCS2-deficient mice may be secondary to the increases in Treg cells and LXA(4) levels. This occurs at the cost of greater infection-associated heart dysfunction, highlighting the relevance of balanced inflammatory and immune responses in preventing severe T. cruzi-induced disease.

Bipolar Androgen Therapy: When Excess Fuel Extinguishes the Fire.

Androgen deprivation therapy (ADT) remains the cornerstone of advanced prostate cancer treatment. However, the progression towards castration-resistant prostate cancer is inevitable, as the cancer cells reactivate androgen receptor signaling and adapt to the castrate state through autoregulation of the androgen receptor. Additionally, the upfront use of novel hormonal agents such as enzalutamide and abiraterone acetate may result in long-term toxicities and may trigger the selection of AR-independent cells through "Darwinian" treatment-induced pressure. Therefore, it is crucial to develop new strategies to overcome these challenges. Bipolar androgen therapy (BAT) is one such approach that has been devised based on studies demonstrating the paradoxical inhibitory effects of supraphysiologic testosterone on prostate cancer growth, achieved through a variety of mechanisms acting in concert. BAT involves rapidly alternating testosterone levels between supraphysiological and near-castrate levels over a period of a month, achieved through monthly intramuscular injections of testosterone plus concurrent ADT. BAT is effective and well-tolerated, improving quality of life and potentially re-sensitizing patients to previous hormonal therapies after progression. By exploring the mechanisms and clinical evidence for BAT, this review seeks to shed light on its potential as a promising new approach to prostate cancer treatment.

Non-neuronal cholinergic machinery present in cardiomyocytes offsets hypertrophic signals.

Recent work has provided compelling evidence that increased levels of acetylcholine (ACh) can be protective in heart failure, whereas reduced levels of ACh secretion can cause heart malfunction. Previous data show that cardiomyocytes themselves can actively secrete ACh, raising the question of whether this cardiomyocyte derived ACh may contribute to the protective effects of ACh in the heart. To address the functionality of this non-neuronal ACh machinery, we used cholinesterase inhibitors and a siRNA targeted to AChE (acetylcholinesterase) as a way to increase the availability of ACh secreted by cardiac cells. By using nitric oxide (NO) formation as a biological sensor for released ACh, we showed that cholinesterase inhibition increased NO levels in freshly isolated ventricular myocytes and that this effect was prevented by atropine, a muscarinic receptor antagonist, and by inhibition of ACh synthesis or vesicular storage. Functionally, cholinesterase inhibition prevented the hypertrophic effect as well as molecular changes and calcium transient alterations induced by adrenergic overstimulation in cardiomyocytes. Moreover, inhibition of ACh storage or atropine blunted the anti-hypertrophic action of cholinesterase inhibition. Altogether, our results show that cardiomyocytes possess functional cholinergic machinery that offsets deleterious effects of hyperadrenergic stimulation. In addition, we show that adrenergic stimulation upregulates expression levels of cholinergic components. We propose that this cardiomyocyte cholinergic signaling could amplify the protective effects of the parasympathetic nervous system in the heart and may counteract or partially neutralize hypertrophic adrenergic effects.

Redox-Active Drug, MnTE-2-PyP5+, Prevents and Treats Cardiac Arrhythmias Preserving Heart Contractile Function.

BACKGROUND: Cardiomyopathies remain among the leading causes of death worldwide, despite all efforts and important advances in the development of cardiovascular therapeutics, demonstrating the need for new solutions. Herein, we describe the effects of the redox-active therapeutic Mn(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin, AEOL10113, BMX-010 (MnTE-2-PyP5+), on rat heart as an entry to new strategies to circumvent cardiomyopathies. METHODS: Wistar rats weighing 250-300 g were used in both in vitro and in vivo experiments, to analyze intracellular Ca2+ dynamics, L-type Ca2+ currents, Ca2+ spark frequency, intracellular reactive oxygen species (ROS) levels, and cardiomyocyte and cardiac contractility, in control and MnTE-2-PyP5+-treated cells, hearts, or animals. Cells and hearts were treated with 20 µM MnTE-2-PyP5+ and animals with 1 mg/kg, i.p. daily. Additionally, we performed electrocardiographic and echocardiographic analysis. RESULTS: Using isolated rat cardiomyocytes, we observed that MnTE-2-PyP5+ reduced intracellular Ca2+ transient amplitude, without altering cell contractility. Whereas MnTE-2-PyP5+ did not alter basal ROS levels, it was efficient in modulating cardiomyocyte redox state under stress conditions; MnTE-2-PyP5+ reduced Ca2+ spark frequency and increased sarcoplasmic reticulum (SR) Ca2+ load. Accordingly, analysis of isolated perfused rat hearts showed that MnTE-2-PyP5+ preserves cardiac function, increases SR Ca2+ load, and reduces arrhythmia index, indicating an antiarrhythmic effect. In vivo experiments showed that MnTE-2-PyP5+ treatment increased Ca2+ transient, preserved cardiac ejection fraction, and reduced arrhythmia index and duration. MnTE-2-PyP5+ was effective both to prevent and to treat cardiac arrhythmias. CONCLUSION: MnTE-2-PyP5+ prevents and treats cardiac arrhythmias in rats. In contrast to most antiarrhythmic drugs, MnTE-2-PyP5+ preserves cardiac contractile function, arising, thus, as a prospective therapeutic for improvement of cardiac arrhythmia treatment.

(-)-Terpinen-4-ol changes intracellular Ca2+ handling and induces pacing disturbance in rat hearts.

(-)-Terpinen-4-ol is a naturally occurring plant monoterpene and has been shown to have a plethora of biological activities. The objective of this study was to investigate the effects of (-)-terpinen-4-ol on the rat heart, a key player in the control and maintenance of arterial blood pressure. The effects of (-)-terpinen-4-ol on the rat heart were investigated using isolated left atrium isometric force measurements, in vivo electrocardiogram (ECG) recordings, patch clamp technique, and confocal microscopy. It was observed that (-)-terpinen-4-ol reduced contraction force in an isolated left atrium at millimolar concentrations. Conversely, it induced a positive inotropic effect and extrasystoles at micromolar concentrations, suggesting that (-)-terpinen-4-ol may have arrhythmogenic activity on cardiac tissue. In anaesthetized animals, (-)-terpinen-4-ol also elicited rhythm disturbance, such as supraventricular tachycardia and atrioventricular block. To investigate the cellular mechanism underlying the dual effect of (-)-terpinen-4-ol on heart muscle, experiments were performed on isolated ventricular cardiomyocytes to determine the effect of (-)-terpinen-4-ol on L-type Ca2+ currents, Ca2+ sparks, and Ca2+ transients. The arrhythmogenic activity of (-)-terpinen-4-ol in vitro and in vivo may be explained by its effect on intracellular Ca2+ handling. Taken together, our data suggest that (-)-terpinen-4-ol has cardiac arrhythmogenic activity.

Cardiorespiratory alterations in rodents experimentally envenomed with Hadruroides lunatus scorpion venom.

BACKGROUND: Hadruroides lunatus is the most abundant scorpion species in the Peruvian central coast, where most of the accidents involving humans are registered. In spite of its prevalence, there are only very few studies on H. lunatus envenomation. The aim of the present study was to analyze the cardiorespiratory alterations caused by H. lunatus envenomation in rodents. METHODS: Wistar rats injected with H. lunatus scorpion venom were submitted to electrocardiography. After euthanasia, rat lungs were collected and histopathologically analyzed. Mouse cardiomyocytes were used to perform immunofluorescence and calcium transient assays. Data were analyzed by ANOVA or Student's t-test. The significance level was set at p < 0.05. RESULTS: It was observed that H. lunatus venom increased heart rate and caused arrhythmia, thereby impairing the heart functioning. Lungs of envenomed animals showed significant alterations, such as diffuse hemorrhage. In addition, immunofluorescence showed that H. lunatus venom was capable of binding to cardiomyocytes. Furthermore, mouse ventricular cardiomyocytes incubated with H. lunatus venom showed a significant decrease in calcium transient, confirming that H. lunatus venom exerts a toxic effect on heart. CONCLUSION: Our results showed that H. lunatus venom is capable of inducing cardiorespiratory alterations, a typical systemic effect of scorpionism, stressing the importance of medical monitoring in envenomation cases.

Dissection of the Effects of Quercetin on Mouse Myocardium.

Quercetin is a plant flavonoid with several biological activities. This study aimed to describe quercetin effects on contractile and electrophysiological properties of the cardiac muscle as well as on calcium handling. Quercetin elicited positive inotropism that was significantly reduced by propranolol indicating an involvement of the sympathetic nervous system. In cardiomyocytes, 30 µM quercetin increased ICa,L at 0 mV from -0.95 ± 0.01 A/F to -1.21 ± 0.08 A/F. The membrane potential at which 50% of the channels are activated (V0.5 ) shifted towards more negative potentials from -13.06 ± 1.52 mV to -19.26 ± 1.72 mV and did not alter the slope factor. Furthermore, quercetin increased [Ca2+ ]i transient by 28% when compared to control. Quercetin accelerated [Ca2+ ]i transient decay time, which could be attributed to SERCA activation. In resting cardiomyocytes, quercetin did not change amplitude or frequency of Ca2+ sparks. In isolated heart, quercetin increased heart rate and decreased PRi, QTc and duration of the QRS complex. Thus, we showed that quercetin activates ß-adrenoceptors, leading to increased L-type Ca2+ current and cell-wide intracellular Ca2+ transient without visible changes in Ca2+ sparks.

Distinct effects of novel naphtoquinone-based triazoles in human leukaemic cell lines.

OBJECTIVES: The aim of this study was to investigate the cytotoxic effect of new 1,4-naphthoquinone- 1,2,3-triazoles, named C2 to C8 triazole derivatives, towards human cancer cell lines. METHODS: The effect on cell viability was assessed by MTT and propidium iodide assays. The cytotoxic effect of C2 and C3 in K562 and HL-60 cells were analyzed by flow cytometry, DNA fragmentation and reactive oxygen species (ROS) production. Western blot and q-PCR procedures were also performed. KEY FINDINGS: C2 and C3 inhibited both K562 and HL-60 cells growth in a concentration-dependent manner. C2 presented the highest cytotoxic activity with an IC50 of approximately 14 µm and 41 µm for HL-60 and K562 cells, respectively, while being less toxic to normal peripheral blood monocyte cells. Both derivatives induced cellular changes in HL-60 cells, characteristic of apoptosis, such as mitochondrial membrane depolarization, phosphatidylserine externalization, increasing sub-G1 phase, DNA fragmentation, downregulating Bcl-2 protein and upregulating Bax protein. In K562 cells, C2 and C3 induced S-phase arrest of cell cycle, which was associated with upregulation of p21. The effect of these derivatives in HL-60 cells can be related to the ROS intracellular level. CONCLUSION: Taken together our results showed that C2 and C3 triazole derivatives presented the best potential for drug design.

Nursing Activities Score and workload in the intensive care unit of a university hospital.

OBJECTIVE: The nursing workload consists of the time spent by the nursing staff to perform the activities for which they are responsible, whether directly or indirectly related to patient care. The aim of this study was to evaluate the nursing workload in an adult intensive care unit at a university hospital using the Nursing Activities Score (NAS) instrument. METHODS: A longitudinal, prospective study that involved the patients admitted to the intensive care unit of a university hospital between March and December 2008. The data were collected daily to calculate the NAS, the Acute Physiology and Chronic Health Evaluation (APACHE II), the Sequential Organ Failure Assessment (SOFA) and the Therapeutic Intervention Scoring System (TISS-28) of patients until they left the adult intensive care unit or after 90 days of hospitalization. The level of significance was set at 5%. RESULTS: In total, 437 patients were evaluated, which resulted in an NAS of 74.4%. The type of admission, length of stay in the intensive care unit and the patients' condition when leaving the intensive care unit and hospital were variables associated with differences in the nursing workload. There was a moderate correlation between the mean NAS and APACHE II severity score (r=0.329), the mean organic dysfunction SOFA score (r=0.506) and the mean TISS-28 score (r=0.600). CONCLUSION: We observed a high nursing workload in this study. These results can assist in planning the size of the staff required. The workload was influenced by clinical characteristics, including an increased workload required for emergency surgical patients and patients who died.

Cholinergic signaling exerts protective effects in models of sympathetic hyperactivity-induced cardiac dysfunction.

Cholinergic control of the heart is exerted by two distinct branches; the autonomic component represented by the parasympathetic nervous system, and the recently described non-neuronal cardiomyocyte cholinergic machinery. Previous evidence has shown that reduced cholinergic function leads to deleterious effects on the myocardium. Yet, whether conditions of increased cholinergic signaling can offset the pathological remodeling induced by sympathetic hyperactivity, and its consequences for these two cholinergic axes are unknown. Here, we investigated two models of sympathetic hyperactivity: i) the chronic beta-adrenergic receptor stimulation evoked by isoproterenol (ISO), and ii) the α2A/α2C-adrenergic receptor knockout (KO) mice that lack pre-synaptic adrenergic receptors. In both models, cholinergic signaling was increased by administration of the cholinesterase inhibitor, pyridostigmine. First, we observed that isoproterenol produces an autonomic imbalance characterized by increased sympathetic and reduced parasympathetic tone. Under this condition transcripts for cholinergic proteins were upregulated in ventricular myocytes, indicating that non-neuronal cholinergic machinery is activated during adrenergic overdrive. Pyridostigmine treatment prevented the effects of ISO on autonomic function and on the ventricular cholinergic machinery, and inhibited cardiac remodeling. α2A/α2C-KO mice presented reduced ventricular contraction when compared to wild-type mice, and this dysfunction was also reversed by cholinesterase inhibition. Thus, the cardiac parasympathetic system and non-neuronal cardiomyocyte cholinergic machinery are modulated in opposite directions under conditions of increased sympathetic drive or ACh availability. Moreover, our data support the idea that pyridostigmine by restoring ACh availability is beneficial in heart disease.

Novel insights into the development of chagasic cardiomyopathy: role of PI3Kinase/NO axis.

BACKGROUND: Chagas' disease is one of the leading causes of heart failure in Latin American countries. Despite its great social impact, there is no direct evidence in the literature explaining the development of heart failure in Chagas' disease. Therefore, the main objective of the study was to investigate the development of the Chagas' disease towards its chronic phase and correlate with modifications in the cellular electrophysiological characteristics of the infected heart. METHODS AND RESULTS: Using a murine model of Chagas' disease, we confirmed and extended previous findings of altered electrocardiogram and echocardiogram in this cardiomyopathy. The observed changes in the electrocardiogram were correlated with the prolonged action potential and reduced transient outward potassium current density. Reduced heart function was associated with remodeling of intracellular calcium handling, altered extracellular matrix content, and to a set of proteins involved in the control of cellular contractility in ventricular myocytes. Furthermore, disruption of calcium homeostasis was partially due to activation of the PI3Kinase/nitric oxide signaling pathway. Finally, we propose a causal link between the inflammatory mediators and heart remodeling during chagasic cardiomyopathy. CONCLUSION: Altogether our results demonstrate that heart failure in Chagas' disease may occur due to electrical and mechanical remodeling of cardiac myocytes, and suggest that AKT/PI3K/NO axis could be an important pharmacological target to improve the disease outcome.

Functional cross-talk between aldosterone and angiotensin-(1-7) in ventricular myocytes.

High serum levels of aldosterone have been linked to the development of cardiac disease. In contrast, angiotensin (Ang)-(1-7) was extensively shown to possess cardioprotective effects, including the attenuation of cardiac dysfunction induced by excessive mineralocorticoid activation in vivo, suggesting possible interactions between these 2 molecules. Here, we investigated whether there is cross-talk between aldosterone and Ang-(1-7) and its functional consequences for calcium (Ca(2+)) signaling in ventricular myocytes. Short-term effects of aldosterone on Ca(2+) transient were assessed in Fluo-4/AM-loaded myocytes. Confocal images showed that Ang-(1-7) had no effect on Ca(2+) transient parameters, whereas aldosterone increased the magnitude of the Ca(2+) transient. Quite unexpectedly, addition of Ang-(1-7) to aldosterone-treated myocytes further enhanced the amplitude of the Ca(2+) transient suggesting a synergistic effect of these molecules. Aldosterone action on Ca(2+) transient amplitude was mediated by protein kinase A, and was related to an increase in Ca(2+) current (I(Ca)) density. Both changes were not altered by Ang-(1-7). When cardiomyocytes were exposed to aldosterone, increased Ca(2+) spark rate was measured. Ang-(1-7) prevented this change. In addition, a NO synthase inhibitor restored the effect of aldosterone on Ca(2+) spark rate in Ang-(1-7)-treated myocytes and attenuated the synergistic effect of these 2 molecules on Ca(2+) transient. These results indicate that NO plays an important role in this cross-talk. Our results bring new perspectives in the understanding of how 2 prominent molecules with supposedly antagonist cardiac actions cross-talk to synergistically amplify Ca(2+) signals in cardiomyocytes.

Current developments in the practice of individual psychoanalytic psychodrama in France.

The authors present the history of individual psychoanalytic psychodrama and its current developments as practised in France. They put forward the technique, objectives and rules, along with the indications, limits and risks that ensue from the specific nature of this therapeutic approach. Through its technical adjustments, individual psychoanalytic psychodrama provides a therapeutic option that is appropriate to the defences prevalent in many patients that cause classical psychotherapies to fail: massive inhibition, operative functioning far removed from affects or in false self mode; phobias, disavowal or splitting of the internal psychic life and emotions; prevalence of short discharge circuits in acted-out behaviours and bodily or visceral complaints and expressions. Psychodrama utilizes these defences not in order to eliminate them but to 'subvert' them so that they can continue to carry out their protective role, in particular ensuring narcissistic continuity. At the same time, psychodrama relaxes these defences and facilitates a possible filtering through of the repressed material. Through the number of actors and the diffraction of transference that this allows, psychodrama provides a possibility of adjusting the potentially traumatic effect of the encounter with the object and the instigation of the transference in the regressive dimension induced by any psychotherapeutic process.

An analysis of the myocardial transcriptome in a mouse model of cardiac dysfunction with decreased cholinergic neurotransmission.

Autonomic dysfunction is observed in many cardiovascular diseases and contributes to cardiac remodeling and heart disease. We previously reported that a decrease in the expression levels of the vesicular acetylcholine transporter (VAChT) in genetically-modified homozygous mice (VAChT KD(HOM)) leads to decreased cholinergic tone, autonomic imbalance and a phenotype resembling cardiac dysfunction. In order to further understand the molecular changes resulting from chronic long-term decrease in parasympathetic tone, we undertook a transcriptome-based, microarray-driven approach to analyze gene expression changes in ventricular tissue from VAChT KD(HOM) mice. We demonstrate that a decrease in cholinergic tone is associated with alterations in gene expression in mutant hearts, which might contribute to increased ROS levels observed in these cardiomyocytes. In contrast, in another model of cardiac remodeling and autonomic imbalance, induced through chronic isoproterenol treatment to increase sympathetic drive, these genes did not appear to be altered in a pattern similar to that observed in VAChT KD(HOM) hearts. These data suggest the importance of maintaining a fine balance between the two branches of the autonomic nervous system and the significance of absolute levels of cholinergic tone in proper cardiac function.

Cardiorespiratory alterations in rodents experimentally envenomed with Hadruroides lunatus scorpion venom

Abstract Background Hadruroides lunatus is the most abundant scorpion species in the Peruvian central coast, where most of the accidents involving humans are registered. In spite of its prevalence, there are only very few studies on H. lunatus envenomation. The aim of the present study was to analyze the cardiorespiratory alterations caused by H. lunatus envenomation in rodents. Methods Wistar rats injected with H. lunatus scorpion venom were submitted to electrocardiography. After euthanasia, rat lungs were collected and histopathologically analyzed. Mouse cardiomyocytes were used to perform immunofluorescence and calcium transient assays. Data were analyzed by ANOVA or Student’s t-test. The significance level was set at p< 0.05. Results It was observed that H. lunatus venom increased heart rate and caused arrhythmia, thereby impairing the heart functioning. Lungs of envenomed animals showed significant alterations, such as diffuse hemorrhage. In addition, immunofluorescence showed that H. lunatus venom was capable of binding to cardiomyocytes. Furthermore, mouse ventricular cardiomyocytes incubated with H. lunatus venom showed a significant decrease in calcium transient, confirming that H. lunatus venom exerts a toxic effect on heart. Conclusion Our results showed that H. lunatus venom is capable of inducing cardiorespiratory alterations, a typical systemic effect of scorpionism, stressing the importance of medical monitoring in envenomation cases.

Cardiorespiratory alterations in rodents experimentally envenomed with Hadruroides lunatus scorpion venom

Abstract Background Hadruroides lunatus is the most abundant scorpion species in the Peruvian central coast, where most of the accidents involving humans are registered. In spite of its prevalence, there are only very few studies on H. lunatus envenomation. The aim of the present study was to analyze the cardiorespiratory alterations caused by H. lunatus envenomation in rodents. Methods Wistar rats injected with H. lunatus scorpion venom were submitted to electrocardiography. After euthanasia, rat lungs were collected and histopathologically analyzed. Mouse cardiomyocytes were used to perform immunofluorescence and calcium transient assays. Data were analyzed by ANOVA or Students t-test. The significance level was set at p 0.05. Results It was observed that H. lunatus venom increased heart rate and caused arrhythmia, thereby impairing the heart functioning. Lungs of envenomed animals showed significant alterations, such as diffuse hemorrhage. In addition, immunofluorescence showed that H. lunatus venom was capable of binding to cardiomyocytes. Furthermore, mouse ventricular cardiomyocytes incubated with H. lunatus venom showed a significant decrease in calcium transient, confirming that H. lunatus venom exerts a toxic effect on heart. Conclusion Our results showed that H. lunatus venom is capable of inducing cardiorespiratory alterations, a typical systemic effect of scorpionism, stressing the importance of medical monitoring in envenomation cases.

Aqueous fraction from Costus spiralis (Jacq.) Roscoe leaf reduces contractility by impairing the calcium inward current in the mammalian myocardium.

ETHNOPHARMACOLOGICAL RELEVANCE: Brazilian folk medicine uses infusion of Costus spiralis leaf to help people to treat arterial hypertension and syndromes of cardiac hyperexcitability. AIM OF THE STUDY: Evaluate the aqueous fraction (AqF) effect on atrial contractility and investigate its mechanism of action. MATERIALS AND METHODS: The AqF effect on the cardiac contractility was studied on isolated electrically driven guinea pig left atria. Atropine and tetraethylammonium (TEA) were employed to investigate whether potassium contributes for the inotropic mechanism of the AqF. The role of calcium in this effect was also studied. This was done by analysing the AqF effect on the Bowditch's phenomenon, as well as by studying whether it could interfere with the concentration-effect curve for CaCl(2), isoproterenol, and BAY K8644. Mice isolated cardiomyocytes were submitted to a whole-cell patch-clamp technique in order to evaluate whether the L-type calcium current participates on the AqF effect. Furthermore, the intracellular calcium transient was studied by confocal fluorescence microscopy. RESULTS: AqF depressed the atrial contractile force. It was the most potent fraction from C. spiralis leaf (EC(50)=305 ± 41 mg/l) (crude extract: EC(50)=712 ± 41; ethyl acetate: EC(50)=788 ± 121; chloroform: EC(50)=8,948 ± 1,346 mg/l). Sodium and potassium content in the AqF was 0.15 mM and 1.91 mM, respectively. Phytochemical analysis revealed phenols, tannins, flavones, xanthones, flavonoids, flavonols, flavononols, flavonones, and saponins. Experiments with atropine and TEA showed that potassium does not participate of the inotropic mechanism of AqF. However, this fraction decreased the force overshoot characteristic of the Bowditch's phenomenon, and shifted the concentration-response curve for CaCl(2) (EC(50) from 1.12 ± 0.07 to 7.23 ± 0.47 mM) indicating that calcium currents participate on its mechanism of action. Results obtained with isoproterenol (1-1,000 pM) and BAY K8644 (5-2000nM) showed that AqF abolished the inotropic effect of these substances. On cardiomyocytes, 48mg/l AqF reduced (∼23%) the L-type calcium current density from -6.3 ± 0.3 to -4.9 ± 0.2 A/F (n=5 cells, p<0.05) and reduced the intracellular calcium transient (∼20%, 4.7 ± 1.2 a.u., n=42 cells to 3.7 ± 1.00 a.u., n=35 cells, p<0.05). However, the decay time of the fluorescence was not changed (control: 860 ± 32 ms, n=42 cells; AqF: 876 ± 26 ms, n=35 cells, p>0.05). CONCLUSIONS: The AqF of C. spiralis leaf depresses myocardial contractility by reducing the L-type calcium current and by decreasing the intracellular calcium transient. Despite the lack of data on the therapeutic dose of AqF used in folk medicine, our results support, at least in part, the traditional use of this plant to treat cardiac disorders.

R(+)-pulegone impairs Ca²+ homeostasis and causes negative inotropism in mammalian myocardium.

The present study aimed to investigate the inotropic effects of R(+)-pulegone, a monoterpene found in plant species belonging to the genus Mentha, on the mammalian heart. In electrically stimulated guinea pig atria, R(+)-pulegone reduced the contractile force (~83%) and decreased the contraction time measured at 50% of the maximum force amplitude (CT(50)) from 45.8 ± 6.2 ms to 36.9 ± 6.2 ms, suggesting that R(+)-pulegone may have an effect on Ca(2+) homeostasis. Nifedipine (40 µM), taken as a positive control, showed a very similar profile. To explore the hypothesis that R(+)-pulegone is somehow affecting Ca(2+) handling, we determined concentration-response curves for both CaCl(2) and BAY K8644. R(+)-pulegone shifted these curves rightward. Using isolated mouse ventricular cardiomyocytes, we measured whole-cell L-type Ca(2+) current and observed an I(Ca,L) peak reduction of 13.7 ± 2.5% and 40.2 ± 2.9% after a 3-min perfusion with 0.11 and 1.1mM of R(+)-pulegone, respectively. In addition, the intracellular Ca(2+) transient was decreased (72.9%) by 3.2mM R(+)-pulegone, with no significant changes in [Ca(2+)](i) transient decay kinetics. Moreover, R(+)-pulegone at 1.1mM prolonged the action potential duration at 10, 50, and 90% of repolarisation. The lengthening of the action potential duration may be attributed to the substantial blockade of the outward K(+) currents caused by 1.1mM of R(+)-pulegone (90.5% at 60 mV). These findings suggest that R(+)-pulegone exerts its negative inotropic effect on mammalian heart mainly by decreasing the L-type Ca(2+) current and the global intracellular Ca(2+) transient.

Angiotensin-(1-7) prevents cardiomyocyte pathological remodeling through a nitric oxide/guanosine 3',5'-cyclic monophosphate-dependent pathway.

The renin-angiotensin (Ang) system plays a pivotal role in the pathogenesis of cardiovascular disease, with Ang II being the major effector of this system. Multiple lines of evidence have shown that Ang-(1-7) exerts cardioprotective effects in the heart by counterregulating Ang II actions. The questions that remain are how and where Ang-(1-7) exerts its effects. By using a combination of molecular biology, confocal microscopy, and a transgenic rat model with increased levels of circulating Ang-(1-7) (TGR[A1-7]3292), we evaluated the signaling pathways involved in Ang-(1-7) cardioprotection against Ang II-induced pathological remodeling in ventricular cardiomyocytes. Rats were infused with Ang II for 2 weeks. We found that ventricular myocytes from TGR(A1-7)3292 rats are protected from Ang II pathological remodeling characterized by Ca(2+) signaling dysfunction, hypertrophic fetal gene expression, glycogen synthase kinase 3beta inactivation, and nuclear factor of activated T-cells nuclear accumulation. Moreover, cardiomyocytes from TGR(A1-7)3292 rats infused with Ang II presented increased expression levels of neuronal NO synthase. To provide a signaling pathway involved in the beneficial effects of Ang-(1-7), we treated neonatal cardiomyocytes with Ang-(1-7) and Ang II for 36 hours. Treatment of cardiomyocytes with Ang-(1-7) prevented Ang II-induced hypertrophy by modulating calcineurin/nuclear factor of activated T-cell signaling cascade. Importantly, antihypertrophic effects of Ang-(1-7) on Ang II-treated cardiomyocytes were prevented by N(G)-nitro-l-arginine methyl ester and 1H-1,2,4oxadiazolo4,2-aquinoxalin-1-one, suggesting that these effects are mediated by NO/cGMP. Taken together, these data reveal a key role for NO/cGMP as a mediator of Ang-(1-7) beneficial effects in cardiac cells.