Myocardial fibrosis and QTc are reduced following treatment with spironolactone or amiloride in stroke survivors: a randomised placebo-controlled cross-over trial

Targeting ASIC1a Promotes Neural Progenitor Cell Migration and Neurogenesis in Ischemic Stroke

Cell replacement therapy using neural progenitor cells (NPCs) has been shown to be an effective treatment for ischemic stroke. However, the therapeutic effect is unsatisfactory due to the imbalanced homeostasis of the local microenvironment after ischemia. Microenvironmental acidosis is a common imbalanced homeostasis in the penumbra and could activate acid-sensing ion channels 1a (ASIC1a), a subunit of proton-gated cation channels following ischemic stroke. However, the role of ASIC1a in NPCs post-ischemia remains elusive. Here, our results indicated that ASIC1a was expressed in NPCs with channel functionality, which could be activated by extracellular acidification. Further evidence revealed that ASIC1a activation inhibited NPC migration and neurogenesis through RhoA signaling-mediated reorganization of filopodia formation, which could be primarily reversed by pharmacological or genetic disruption of ASIC1a. In vivo data showed that the knockout of the ASIC1a gene facilitated NPC migration and neurogenesis in the penumbra to improve behavioral recovery after stroke. Subsequently, ASIC1a gain of function partially abrogated this effect. Moreover, the administration of ASIC1a antagonists (amiloride or Psalmotoxin 1) promoted functional recovery by enhancing NPC migration and neurogenesis. Together, these results demonstrate targeting ASIC1a is a novel strategy potentiating NPC migration toward penumbra to repair lesions following ischemic stroke and even for other neurological diseases with the presence of niche acidosis.

Physiology of a Forgotten Electrolyte-Magnesium Disorders

Magnesium (Mg²⁺) is the second most common intracellular cation and the fourth most abundant element on earth. However, Mg²⁺ is a frequently overlooked electrolyte and often not measured in patients. While hypomagnesemia is common in 15% of the general population, hypermagnesemia is typically only found in preeclamptic women after Mg²⁺ therapy and in patients with ESRD. Mild to moderate hypomagnesemia has been associated with hypertension, metabolic syndrome, type 2 diabetes mellitus, CKD, and cancer. Nutritional Mg²⁺ intake and enteral Mg²⁺ absorption are important for Mg²⁺ homeostasis, but the kidneys are the key regulators of Mg²⁺ homeostasis by limiting urinary excretion to less than 4% while the gastrointestinal tract loses over 50% of the Mg²⁺ intake in the feces. Here, we review the physiological relevance of Mg²⁺, the current knowledge of Mg²⁺ absorption in the kidneys and the gut, the different causes of hypomagnesemia, and a diagnostic approach on how to assess Mg²⁺ status. We highlight the latest discoveries of monogenetic conditions causing hypomagnesemia, which have enhanced our understanding of tubular Mg²⁺ absorption. We will also discuss external and iatrogenic causes of hypomagnesemia and advances in the treatment of hypomagnesemia.

The prognostic value of P-wave dispersion and left atrial functions assessed with three-dimensional echocardiography in patients with cirrhosis

BACKGROUND

Cirrhotic cardiomyopathy (CCM) is a well-known entity. The aim of this study was to compare left atrial three-dimensional (3D) volume and P-wave dispersion (PWd) in patients with cirrhosis and a healthy population. The secondary purpose was to assess the left phasic volumes and reservoir functions with 3D echocardiography for the prediction of an increased risk of poor outcomes in patients with cirrhosis.

METHODS

The study included 50 patients with cirrhosis and 43 healthy control subjects without atrial fibrillation. All patients were assessed with two-dimensional (2D), 3D, and tissue Doppler transthoracic echocardiography. The PWd was calculated using a 12-lead surface electrocardiogram (ECG). Cirrhotic patients were followed up for 2.5 years for the evaluation of poor outcomes and the development of atrial fibrillation.

RESULTS

Patients with cirrhosis were observed to have significantly higher left atrial phasic volumes such as minimal left atrial volume (3D-LAVmin, P = 0.004) and indexed LAVmin (3D-LAVImin, P = 0.0001), and significantly decreased left atrial reservoir functions such as left atrial emptying volume (3D-LAEV, P = 0,001), left atrial ejection fraction (3D-LAEF, P = 0,001) on 3D echocardiography. PWd was determined to be significantly longer in the cirrhotic group compared with the control group (P = 0.003). In the 2.5-year follow-up period, poor outcomes occurred in 34 patients (22 patients died, six patients had liver transplantation, six patients developed atrial fibrillation/AHRE episodes). In Cox regression analysis, the MELD score (HR, 1.16 (1.06-1.26), P = 0.001) and 3D-LAVImin (HR, 0.95 (0.86-1.00), P = 0.040) were significantly associated with all-cause mortality. Cirrhotic patients with LAVImin of >15 ml/m2 were seen to have poor survival (long rank P = 0.033).

CONCLUSION

The results of this study showed that patients with cirrhosis had higher left atrial volume, longer PWd and worse diastolic functions compared with the control group. Higher disease severity scores were associated with left atrial function and volume. In addition, left atrial volume measured with 3DE was a strong predictor of future adverse events, and minimal left atrial volumes had a higher prognostic value than any other left atrial function indices.

Systematic evaluation of structure-property relationships and pharmacokinetics in 6-(hetero)aryl-substituted matched pair analogs of amiloride and 5-(N,N-hexamethylene)amiloride

The K+-sparing diuretic amiloride elicits anticancer activities in multiple animal models. During our recent medicinal chemistry campaign aiming to identify amiloride analogs with improved properties for potential use in cancer, we discovered novel 6-(hetero)aryl-substituted amiloride and 5-(N,N-hexamethylene)amiloride (HMA) analogs with up to 100-fold higher potencies than the parent compounds against urokinase plasminogen activator (uPA), one of amiloride's putative anticancer targets, and no diuretic or antikaliuretic effects. Here, we report the systematic evaluation of structure-property relationships (lipophilicity, aqueous solubility and in vitro metabolic stability in human and mouse liver microsomes) in twelve matched pair analogs selected from our 6-substituted amiloride and HMA libraries. Mouse plasma stability, plasma protein binding, Caco-2 cell permeability, cardiac ion channel activity and pharmacokinetics in mice (PO and IV) and rats (IV) are described alongside amiloride and HMA comparators for a subset of the four most promising matched-pair analogs. The findings combined with earlier uPA activity/selectivity and other data ultimately drove selection of two analogs (AA1-39 and AA1-41) that showed efficacy in separate mouse cancer metastasis studies.

Spontaneous Recurrent Seizures Mediated Cardiac Dysfunction via mTOR Pathway Upregulation: A Putative Target for SUDEP Management

Background:

Alteration in electrophysiology, leading to cardiac dysfunction and subsequently a nontraumatic death is a complication of epilepsy known as “SUDEP” (Sudden Unexpected Death in Epilepsy).

Aims:

The present study was designed to understand the molecular changes and cardiac parameters during different phases of epileptogenesis in lithium-pilocarpine (Li-pilo) rat model of epilepsy.

Methods:

The animals were exposed to Li-pilo to induce Spontaneous Recurrent Seizures (SRS). Noninvasive blood pressure and electrocardiography was recorded at 7th, 28th and 75th day following pilocarpine administration, considered as latent, initial and late SRS phases, respectively. The serum biochemistry, cardiac histopathology, protein and mRNA expressions were studied, following electrocardiography on day 75.

Results:

The mean arterial pressure decreased during the latent phase, thereafter it progressively increased during the initial and the late SRS phases, as compared to the basal and the latent phase. Histopathological analysis of the heart sections indicated hypertrophy, degenerative changes and fibrous tissue deposition in epileptic animals, along with increased levels of lactate dehydrogenase and creatine kinase-MB in the serum. The expression of HIF-1α, phospho-S6, phospho-mTOR, TGF-β, collagen I and Na+/K+-ATPase α1 proteins, and mRNA levels of HIF-1α, mTOR, Rps6, Scn1b, Scn3b, Nav1.5 and TGF-β were increased in the cardiac tissue of epileptic animals, as compared to control.

Conclusion:

Our results conclusively showed that Li-pilo-induced SRS leads to cardiac dysfunction via mTOR pathway upregulation, thus suggested the regulatory control of mTOR pathway as a potential target for SUDEP management.

Hydrochlorothiazide and alternative diuretics versus renin-angiotensin system inhibitors for the regression of left ventricular hypertrophy: a head-to-head meta-analysis

BACKGROUND

Found in 36-41% of hypertension, elevated left ventricular mass (LVM) independently predicts cardiovascular events and total mortality. Conversely, drug-induced regression of LVM predicts improved outcomes. Previous studies have favored renin-angiotensin system inhibitors (RASIs) over other antihypertensives for reducing LVM but ignored differences among thiazide-type diuretics. From evidence regarding potency, cardiovascular events, and electrolytes, we hypothesized a priori that 'CHIP' diuretics [CHlorthalidone, Indapamide and Potassium-sparing Diuretic/hydrochlorothiazide (PSD/HCTZ)] would rival RASIs for reducing LVM.

METHOD AND RESULTS

Systematic review yielded 12 relevant double-blind randomized trials. CHIPs were more closely associated with reduced LVM than HCTZ (P = 0.004), indicating that RASIs must be compared with each diuretic separately. Publication bias favoring RASIs was corrected by cumulative analysis. For reducing LVM, HCTZ tended to be less effective than RASIs. However, the following surpassed RASIs: chlorthalidone Hedge's G: -0.37 (95% CI -0.72 to -0.02), P = 0.036; indapamide -0.20 (-0.39 to -0.01), P = 0.035; all CHIPs combined (with 61% of patients in one trial) -0.25 (-0.41to -0.09), P = 0.002. Statistical significance (P < 0.05) did not depend on any one trial. CHIPs reduction in LVM was 37% greater than that from RASIs. CHIPs superiority tended to increase with trial duration, from a negligible effect at 0.5 year to a maximal effect at 0.9-1.0 years: -0.26 (-0.43 to -0.09), P = 0.003. Fifty-eight percent of patients had information on echocardiographic components of LVM: relative to RASIs, CHIPs significantly reduced end-diastolic LV internal dimension (EDLVID): -0.18 (-0.36 to -0.00), P = 0.046. Strength of evidence favoring CHIPs over RASIs was at least moderate.

CONCLUSION

In these novel results in patients with hypertension, CHIPs surpassed RASIs for reducing LVM and EDLVID.

Mineralocorticoid Receptor and Cardiovascular Disease

Activation of the mineralocorticoid receptor (MR) in the distal nephron by its ligand, aldosterone, plays an important role in sodium reabsorption and blood pressure regulation. However, expression of the MR goes beyond the kidney. It is expressed in a variety of other tissues in which its activation could lead to tissue injury. Indeed, MR activation in the cardiovascular (CV) system has been shown to promote hypertension, fibrosis, and inflammation. Pharmacological blockade of the MR has protective effects in several animal models of CV disease. Furthermore, the use of MR antagonists is beneficial for heart failure patients, preventing mortality and morbidity. A better understanding of the implications of the MR in the setting of CV diseases is critical for refining treatments and improving patient care. The mechanisms involved in the deleterious effects of MR activation are complex and include oxidative stress, inflammation, and fibrosis. This review will discuss the pathological role of the MR in the CV system and the major mechanisms underlying it.

Subclinical ventricular repolarization abnormality in uncontrolled compared with controlled treated hypertension

Background

Antihypertensive medications have variable effects on the duration of the QT interval. This study aims to demonstrate the subclinical ventricular conduction defect in treating hypertensive patients taking in consideration the status of the blood pressure control with the antihypertensive agents.

Methods

This cross-section study was performed at the Departments of Physiology and Pharmacology, College of Medicine, Al-Mustansiriya University, Baghdad, Iraq. A total number of 97 hypertensive patients (30 males and 67 females) were eligible to enroll in the study. The patients were grouped into controlled hypertension (Group I) and uncontrolled hypertension (Group II). Each participant is subjected to the electrocardiograph (ECG) investigation. A QT nomogram plot used to identify the patients who are vulnerable or at risk of developing cardiac arrhythmias.

Results

There were no significant differences in the values of the electrocardiogram determinants between Group I and Group II. Abnormal prolonged QTcB interval observed in 18 out of 80 (22.5%) patients of Group II compared with 4 out of 17. The JT index value of ≥112 was observed in 20 out of 80 (25%) patients of Group II compared with 6 out of 17 (35.3%) patients of Group I. A significant correlation between the QTcB duration with JT index observed in both Groups I and II.

Conclusion

Patients with hypertension have variability in ventricular repolarization (QTcB and JT) irrespective of their blood pressure control putting them at higher risk of cardiac arrhythmias.

Spironolactone Attenuates Doxorubicin-induced Cardiotoxicity in Rats

INTRODUCTION

In this study, we examined whether spironolactone (SP) could inhibit doxorubicin (DOX)-induced cardiotoxicity in the rat heart.

METHODS

Rats were randomized into four groups (n = 6): (1) the control group; (2) the SP group; (3) the DOX group; and (4) the SP + DOX group. The rats were evaluated for electrocardiography and cardiac function. The cardiac collagen, cardiomyocyte apoptosis, and the remodeling-related proteins were determined.

RESULTS

Rats treated with DOX showed prolongation of QTc and decreased left ventricular ejection fraction (EF) and fractional shortening (FS) (P < 0.05) showed left ventricular end-diastolic dimensions (LVEDD) and left ventricular end-systolic dimensions (LVESD) were significantly increased (P < 0.05). SP prevented these pathophysiological alterations (P < 0.05). In DOX-treated group, cardiac fibrosis, apoptotic cell number, and cardiac collagen volume fraction were higher than control group (P < 0.05); these effects were prevented by cotreatment of SP (P < 0.05). Moreover, the expressions of TGF-β1 and phosphorylated-Smad3 were increased after DOX treatment (P < 0.05) and significantly reduced by coadministration of SP (P < 0.05).

CONCLUSIONS

This study show that SP may have a protective effect on DOX-induced cardiotoxicity.

Emerging Roles of the Mineralocorticoid Receptor in Pathology: Toward New Paradigms in Clinical Pharmacology

The mineralocorticoid receptor (MR) and its ligand aldosterone are the principal modulators of hormone-regulated renal sodium reabsorption. In addition to the kidney, there are several other cells and organs expressing MR, in which its activation mediates pathologic changes, indicating potential therapeutic applications of pharmacological MR antagonism. Steroidal MR antagonists have been used for decades to fight hypertension and more recently heart failure. New therapeutic indications are now arising, and nonsteroidal MR antagonists are currently under development. This review is focused on nonclassic MR targets in cardiac, vascular, renal, metabolic, ocular, and cutaneous diseases. The MR, associated with other risk factors, is involved in organ fibrosis, inflammation, oxidative stress, and aging; for example, in the kidney and heart MR mediates hormonal tissue-specific ion channel regulation. Genetic and epigenetic modifications of MR expression/activity that have been documented in hypertension may also present significant risk factors in other diseases and be susceptible to MR antagonism. Excess mineralocorticoid signaling, mediated by aldosterone or glucocorticoids binding, now appears deleterious in the progression of pathologies that may lead to end-stage organ failure and could therefore benefit from the repositioning of pharmacological MR antagonists.

Recent advances in cirrhotic cardiomyopathy

Cirrhotic cardiomyopathy, a cardiac dysfunction presented in patients with cirrhosis, represents a recently recognized clinical entity. It is characterized by altered diastolic relaxation, impaired contractility, and electrophysiological abnormalities, in particular prolongation of the QT interval. Several mechanisms seem to be involved in the pathogenesis of cirrhotic cardiomyopathy, including impaired function of beta-receptors, altered transmembrane currents, and overproduction of cardiodepressant factors, like nitric oxide, tumor necrosis factor α, and endogenous cannabinoids. Diastolic dysfunction is the first manifestation of cirrhotic cardiomyopathy and reflects the increased stiffness of the cardiac mass, which leads to delayed left ventricular filling. On the other hand, systolic incompetence is presented later, is usually unmasked during pharmacological or physical stress, and predisposes to the development of hepatorenal syndrome. The prolongation of QT is found in about 50 % of cirrhotic patients, but rarely leads to fatal arrhythmias. Cirrhotics with blunted cardiac function seem to have poorer survival rates compared to those without, and the risk is particularly increased during the insertion of transjugular intrahepatic portosystemic shunt or liver transplantation. Till now, there is no specific treatment for the management of cirrhotic cardiomyopathy. New agents, targeting to its pathogenetical mechanisms, may play some role as future therapeutic options.

Arrhythmia risk in liver cirrhosis

Interactions between the functioning of the heart and the liver have been described, with heart diseases affecting the liver, liver diseases affecting the heart, and conditions that simultaneously affect both. The heart is one of the most adversely affected organs in patients with liver cirrhosis. For example, arrhythmias and electrocardiographic changes are observed in patients with liver cirrhosis. The risk for arrhythmia is influenced by factors such as cirrhotic cardiomyopathy, cardiac ion channel remodeling, electrolyte imbalances, impaired autonomic function, hepatorenal syndrome, metabolic abnormalities, advanced age, inflammatory syndrome, stressful events, impaired drug metabolism and comorbidities. Close monitoring of cirrhotic patients is needed for arrhythmias, particularly when QT interval-prolonging drugs are given, or if electrolyte imbalances or hepatorenal syndrome appear. Arrhythmia risk may persist after liver transplantation due to possible QT interval prolongation, persistence of the parasympathetic impairment, post-transplant reperfusion and chronic immunosuppression, as well as consideration of the fact that the transplant itself is a stressful event for the cardiovascular system. The aims of the present article were to provide a review of the most important data regarding the epidemiology, pathophysiology, and biomarkers of arrhythmia risk in patients with liver cirrhosis, to elucidate the association with long-term outcome, and to propose future research directions.