Valsartan reduced the vulnerability to atrial fibrillation by preventing action potential prolongation and conduction slowing in castrated male mice

Cognitive changes in patients with unipolar TRD treated with IV ketamine: A systematic review

BACKGROUND

Unipolar treatment-resistant depression (MDD-TRD) is associated with neurocognitive impairment. Ketamine, an emerging treatment for MDD-TRD, may have neurocognitive benefits, but evidence remains limited.

METHODS

We conducted a systematic search on EMBASE, Google Scholar, PsycINFO, and PubMed and included studies exploring the cognitive effects of intravenous (IV) ketamine treatment in the management of MDD-TRD following the PRISMA guidelines. We analyzed cognitive scale score changes pre- and post-IV ketamine treatment and the quality of the evidence using the Cochrane risk of bias tool and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

RESULTS

Out of 1171 identified studies, fourteen studies were included in this study. Most studies reported positive cognitive outcomes post-ketamine treatment, including improvements in processing speed, working memory, verbal and visual memory, executive function, attention, emotional processing, and auditory verbal episodic memory. Variability existed, with one study reporting negative effects on verbal memory. Overall, studies exhibited a low risk of bias.

LIMITATIONS

Several limitations impacted the results observed, including confining our scope to articles in English, heterogeneity of the included studies, small sample sizes, and the predominance of a female, Western, and Caucasian population, constraining the generalizability of the findings.

CONCLUSIONS

IV ketamine treatment shows promise in improving neurocognitive function in MDD-TRD patients. However, further research is warranted to elucidate long-term effects, control for confounders such as concomitant medications, and explore neurocognitive subgroups within the TRD population. These findings underscore the need for comprehensive assessment and management of cognitive symptoms in TRD, informing future clinical practice.

Association between polymorphisms in connexin 40 gene (Cx40) and risk of atrial fibrillation: a meta-analysis based on 3,452 subjects

INTRODUCTION

Atrial fibrillation (AF) is a common cardiac arrhythmia that is associated with heart failure and stroke, leading sometimes to death. But the pathogenesis of AF remains unclear. Numerous studies have investigated whether the connexin 40 (Cx40) polymorphisms influences the risk of AF, but the results are controversial.

METHODS

We searched English and Chinese databases and calculated the odds ratio (OR) and 95% confidence interval (CI) to examine the existence of genetic associations between the Cx40 polymorphisms and the risk of AF. All relevant studies were screened and meta-analyzed using Review Manager 5.0.

RESULTS

A total of 12 studies, including 10 studies for -44 polymorphism (rs35594137) and 4 studies for -26 polymorphism (rs10465885), were identified for the meta-analysis. For -44 polymorphism, the results showed a significantly increased risk of AF in the five genetic models in the overall analysis. Furthermore, in subgroup analysis, increased AF risks were also observed in Asian and non-Asian populations. For -26 polymorphism, the overall OR revealed an increased risk of AF in dominant model. In subgroup analysis, increased AF risk was only found in recessive genetic model of the Asian population.

CONCLUSIONS

The Cx40 polymorphisms were positively associated with AF in both populations, especially on -44 polymorphism.

Connexin Lateralization Contributes to Male Susceptibility to Atrial Fibrillation

Men have a higher risk of developing atrial fibrillation (AF) than women, though the reason for this is unknown. Here, we compared atrial electrical and structural properties in male and female mice and explored the contribution of sex hormones. Cellular electrophysiological studies revealed that action potential configuration, Na+ and K+ currents were similar in atrial myocytes from male and female mice (4–5 months). Immunofluorescence showed that male atrial myocytes had more lateralization of connexins 40 (63 ± 4%) and 43 (66 ± 4%) than females (Cx40: 45 ± 4%, p = 0.006; Cx43: 44 ± 4%, p = 0.002), with no difference in mRNA expression. Atrial mass was significantly higher in males. Atrial myocyte dimensions were also larger in males. Atrial fibrosis was low and similar between sexes. Orchiectomy (ORC) abolished sex differences in AF susceptibility (M: 65%; ORC: 38%, p = 0.050) by reducing connexin lateralization and myocyte dimensions. Ovariectomy (OVX) did not influence AF susceptibility (F: 42%; OVX: 33%). This study shows that prior to the development of age-related remodeling, male mice have more connexin lateralization and larger atria and atrial myocyte than females. Orchiectomy reduced AF susceptibility in males by decreasing connexin lateralization and atrial myocyte size, supporting a role for androgens. These sex differences in AF substrates may contribute to male predisposition to AF.

Effects of Sacubitril/Valsartan on the Expression of CaMKII/Cav1.2 in Atrial Fibrillation Stimulation Rabbit Model

Background and Objective. Atrial fibrillation (AF) is linked to high morbidity and death rates throughout the world due to limited therapeutic options and thus presents a major challenge to the developed and developing countries. In this study, we aim to investigate the influence of sacubitril/valsartan (sac/val) treatment on the calmodulin-dependent protein kinase II (CaMKII)/Cav1.2 expression in AF models. Methods. Overall, 18 rabbits were randomly divided into control, pacing (600 beats/min), and pacing+sac/val groups. The rabbits in the pacing+sac/val cohort received oral sac/val (10 mg/kg twice daily) across the 21-day investigation period. After three weeks, the atrial effective refractory period (AERP) and AF induction rate were compared. HL-1 cultures were exposed to fast pacing (24 h) with and without LBQ657 (active sacubitril form)/valsartan. Western blots were used for detecting Cav1.2 and CaMKII expression within atrial muscles of the rabbits and HL-1 cultures of AF model. Results. In comparison to the sham cohort, the AF induction rate was markedly increased together with AERP reduction within pacing cohort. Such changes were markedly rescued through sac/val treatment in pacing+sac/val cohort. The proteomic expression profiles of CaMKII and Cav1.2 showed that the CaMKII expression was markedly upregulated, while Cav1.2 expression was downregulated in the pacing cohort. Importantly, these effects were absent in pacing+sac/val cohort. Conclusion. Results of this study show that sac/val treatment regulates the expression of CaMKII/Cav1.2 and could alter this pathway in atrial rapid electrical stimulation models. Therefore, this investigation could contribute to a novel strategy in AF therapeutics in clinical settings.

The Impact of Testosterone on the QT Interval: A Systematic Review

Humans and mammals have sex-specific differences in cardiac electrophysiology, linked to the action of sex hormones in the cardiac muscle. These hormones can upregulate or downregulate the expression of ionic channels modulating the cardiac cycle through genomic and non-genomic interactions. Systematic search in PubMed, Medline and EMBASE including keywords pertaining to testosterone and QT interval. Included experimental studies and observation studies and case reports presenting the results of testosterone administration, excess or deficiency in humans and animals. Testosterone has been shown to shorten the action potential duration, by enhancing the expression of K⁺ channels and downregulating I_CaL increasing the repolarization reserve of the cardiac muscle. This effect has been observed in both genders and animals. Testosterone deficient states can promote arrhythmogenesis. The evidence in this paper may be used to guide clinical considerations, such as increased clinical surveillance of patients in testosterone deficient states using ECG.

Prolonged duration of repolarization and decreased conduction velocity in the atrial myocardium after hypothermic ischemia-reperfusion may be related to expressions of inward rectifier potassium channel 2.1 protein and connexin 40

OBJECTIVES

The study aimed to determine the role of inward rectifier potassium channel 2.1 protein and connexin 40 expressions in regulating the duration of repolarization and conduction velocity of right atrial myocardium in rats following hypothermic ischemia-reperfusion.

METHODS

The Langendorff isolated rat cardiac perfusion models were divided into control (C) and hypothermic ischemia-reperfusion groups, with 8 models in group C and 16 models in group ischemia-reperfusion. Depending on the incidence of atrial arrhythmia after reperfusion, the models in group ischemia-reperfusion were further divided into reperfusion non-atrial arrhythmia or reperfusion atrial arrhythmia subgroup. Right atrial monophasic action potential duration at 50% and 90% of repolarization after 30 minutes of continuous perfusion in group C and group ischemia-reperfusion (T0), 105 minutes of continuous perfusion in group C or after 15 minutes of reperfusion in group ischemia-reperfusion (T1) and 120 minutes of continuous perfusion in group C or 30 minutes of reperfusion in group ischemia-reperfusion (T2) were recorded. Right atrial conduction velocity and effective refractory period were recorded at T2. Then, the expressions of inward rectifier potassium channel 2.1 protein and connexin 40 in the right atrial myocardium were detected.

RESULTS

Monophasic action potential duration at 50% and 90% were higher at T1 and T2 than those at T0 in subgroup reperfusion atrial arrhythmia (p < 0.05); monophasic action potential duration at 50% in subgroup reperfusion atrial arrhythmia were larger than group C and subgroup reperfusion non-atrial arrhythmia at T1 and T2 (p < 0.05); monophasic action potential duration at 90% in subgroup reperfusion atrial arrhythmia were larger than group C and subgroup reperfusion non-atrial arrhythmia at T1 and T2 (p < 0.05); effective refractory period in subgroup reperfusion atrial arrhythmia was greater than that in group C and subgroup reperfusion non-atrial arrhythmia, and the conduction velocity and the expressions of inward rectifier potassium channel 2.1 protein and connexin 40 were significantly lower than group C and subgroup reperfusion non-atrial arrhythmia (p < 0.05).

CONCLUSIONS

The prolonged duration of repolarization and a decrease in conduction velocity of the atrial myocardium occur in rats after hypothermic ischemia-reperfusion. These observed effects may be related to the downregulated expressions of connexin 40 and inward rectifier potassium channel 2.1.

RETRACTED: Safety of radiofrequency ablation for reducing inflammatory cytokine levels and the left atrial diameter in patients with atrial fibrillation

Objective

To investigate the safety of radiofrequency ablation for reducing inflammatory cytokines and the left atrial diameter in patients with atrial fibrillation (AF).

Methods

A total of 200 patients with AF who were admitted to our hospital from December 2015 to April 2017 were included in this prospective analysis. Fifty patients were treated with conventional AF medication alone (AF medication group) and 50 patients received radiofrequency ablation (RFA) on the basis of conventional medication (RFA group).

Results

After treatment, the AF medication group showed significantly higher levels of high-sensitivity C-reactive protein, interleukin-6, carboxyterminal propeptide of type-I procollagen, procollagen type III N-terminal propeptide, and matrix metallopeptidase-9 than the RFA group. The AF medication group had a significantly lower activated partial thromboplastin time, thrombin time, and prothrombin time than the RFA group. A significantly smaller left atrial diameter was observed in both groups after treatment, but this decrease was more pronounced in the RFA group than in the AF medication group. The total treatment efficacy rate was significantly lower in the AF medication group than in the RFA group.

Conclusions

For patients with AF, RFA leads to a lower incidence of inflammatory responses, faster recovery of cardiac function, and good safety.

Sacubitril/valsartan attenuates atrial electrical and structural remodelling in a rabbit model of atrial fibrillation

Atrial structural and electrical remodelling play important roles in atrial fibrillation (AF). Sacubitril/valsartan attenuates cardiac remodelling in heart failure. However, the effect of sacubitril/valsartan on AF is unclear. The aim of this study was to evaluate the effect of sacubitril/valsartan on atrial electrical and structural remodelling in AF and investigate the underlying mechanism of action. Thirty-three rabbits were randomized into sham, RAP, and sac/val groups. HL-1 cells were subjected to control treatment or rapid pacing with or without LBQ657 and valsartan. Echocardiography, atrial electrophysiology, and histological examination were performed. The concentration of Ca²⁺ and expression levels of calcineurin, NFAT, p-NFAT, Cav1.2, collagen Ⅰ and Ⅲ, ANP, BNP, CNP, NT-proBNP, and ST2 in HL-1 cells, and I_caL in left atrial cells, were determined. We observed that compared to that in the sham group, the atrium and right ventricle were enlarged, myocardial fibrosis was markedly higher, AF inducibility was significantly elevated, and atrial effective refractory periods were shortened in the RAP group. These effects were significantly reversed by sacubitril/valsartan. Compared to that in the sham group, collagen Ⅰ and Ⅲ, NT-proBNP, ST2, calcineurin, and NFAT were significantly up-regulated, while p-NFAT and Ca_v1.2 were down-regulated in the RAP group, and sacubitril/valsartan inhibited these changes. Ca²⁺ concentration increased and I_CaL density decreased in in vivo and in vitro AF models, reversed by sacubitril/valsartan. Sacubitril/valsartan attenuates atrial electrical remodelling and ameliorates structure remodelling in AF. This study paves the way for the possibility of clinical use of sacubitril/valsartan in AF patients.

High hydrostatic pressure induces atrial electrical remodeling through angiotensin upregulation mediating FAK/Src pathway activation

Hypertension is an independent risk factor for atrial fibrillation (AF), although its specific mechanisms remain unclear. Previous research has been focused on cyclic stretch, ignoring the role of high hydrostatic pressure. The present study aimed to explore the effect of high hydrostatic pressure stimulation on electrical remodeling in atrial myocytes and its potential signaling pathways. Experiments were performed on left atrial appendages from patients with chronic AF or sinus rhythm, spontaneously hypertensive rats (SHRs) treated with or without valsartan (10 mg/kg/day) and HL-1 cells were exposed to high hydrostatic pressure using a self-developed device. Whole-cell patch-clamp recordings and western blots demonstrated that the amplitudes of I_Ca,L, I_to, and I_Kur were reduced in AF patients with corresponding changes in protein expression. Angiotensin protein levels increased and Ang1-7 decreased, while focal adhesion kinase (FAK) and Src kinase were enhanced in atrial tissue from AF patients and SHRs. After rapid atrial pacing, AF inducibility in SHR was significantly higher, accompanied by a decrease in I_Ca,L, upregulation of I_to and I_Kur, and a shortened action potential duration. Angiotensin upregulation and FAK/Src activation in SHR were inhibited by angiotensin type 1 receptor inhibitor valsartan, thus, preventing electrical remodeling and reducing AF susceptibility. These results were verified in HL-1 cells treated with high hydrostatic pressure, and demonstrated that electrical remodeling regulated by the FAK-Src pathway could be modulated by valsartan. The present study indicated that high hydrostatic pressure stimulation increases AF susceptibility by activating the renin-angiotensin system and FAK-Src pathway in atrial myocytes.