Cav1.3 channels play a critical role in the regulation of [Ca(2+)]i dynamics, providing an unanticipated mechanism for triggering local [Ca(2+)]i releases and thereby controlling pacemaker activity. Our study also provides an additional pathophysiological mechanism for congenital SAN dysfunction and heart block linked to Cav1.3 loss of function in humans.

Parasympathetic regulation of sinoatrial node (SAN) pacemaker activity modulates multiple ion channels to temper heart rate. The functional role of the G-protein–activated K+ current (IKACh) in the control of SAN pacemaking and heart rate is not completely understood. We have investigated the functional consequences of loss of IKACh in cholinergic regulation of pacemaker activity of SAN cells and in heart rate control under physiological situations mimicking the fight or flight response. We used knockout mice with loss of function of the Girk4 (Kir3.4) gene (Girk4−/− mice), which codes for an integral subunit of the cardiac IKACh channel. SAN pacemaker cells from Girk4−/− mice completely lacked IKACh. Loss of IKACh strongly reduced cholinergic regulation of pacemaker activity of SAN cells and isolated intact hearts. Telemetric recordings of electrocardiograms of freely moving mice showed that heart rate measured over a 24-h recording period was moderately increased (10%) in Girk4−/− animals. Although the relative extent of heart rate regulation of Girk4−/− mice was similar to that of wild-type animals, recovery of resting heart rate after stress, physical exercise, or pharmacological β-adrenergic stimulation of SAN pacemaking was significantly delayed in Girk4−/− animals. We conclude that IKACh plays a critical role in the kinetics of heart rate recovery to resting levels after sympathetic stimulation or after direct β-adrenergic stimulation of pacemaker activity. Our study thus uncovers a novel role for IKACh in SAN physiology and heart rate regulation.

The BS pattern of p.S216L might result from a decrease in I(Na) density, which masked gating abnormalities that might otherwise result in a LQT phenotype. The p.H558R polymorphism decreased p.S216L expressivity, partly by lessening p.S216L effects and partly through the induction of further gating abnormalities suitable to blunt p.S216L effects during repolarization.

Rationale: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare disease, manifested by syncope or sudden death in children or young adults under stress conditions. Mutations in the Ca 2+ release channel/ryanodine receptor (RyR2) gene account for about 60% of the identified mutations. Recently, we found and described a mutation in RyR2 N-terminal domain, RyR2 R420Q . Objective: To determine the arrhythmogenic mechanisms of this mutation. Methods and Results: Ventricular tachycardias under stress conditions were observed in both CPVT patients and KI mice. During action potential recording (by patch-clamp in KI mouse cardiomyocytes and by microelectrodes in mutant hiPSC-CM) we observed an increased occurrence of delayed after-depolarizations (DADs) under isoproterenol stimulation, associated with increased Ca 2+ waves during confocal Ca 2+ recording in both mouse and human RyR2 R420Q cardiomyocytes. In addition, Ca 2+ -induced Ca 2+ -release, as well as a rough indicator of fractional Ca 2+ release, were higher and Ca 2+ sparks longer in the RyR2 R420Q expressing cells. At the ultrastructural nanodomain level, we observed smaller RyR2 clusters and widened junctional sarcoplasmic reticulum (jSR) measured by g-STED super-resolution and electronic microscopy, respectively. The increase in jSR width might be due to the impairment of RyR2 R420Q binding to junctophilin-2, as there were less junctophilin-2 co-immunoprecipitated with RyR2 R420Q . At the single current level, the RyR2R420Q channel dwells longer in the open state at low [Ca 2+ ] i , but there is predominance of a subconductance state. The latter might be correlated with an enhanced interaction between the N-terminus and the core solenoid, a RyR2 inter-domain association that has not been previously implicated in the pathogenesis of arrhythmias and sudden cardiac death. Conclusions: The RyR2 R420Q CPVT mutation modifies the interdomain interaction of the channel and weaken its association with junctophillin-2. These defects may underlie both nanoscale disarrangement of the dyad and channel dysfunction.

The solute carrier (SLC) superfamily represents the biggest family of transporters with important roles in health and disease. Despite being attractive and druggable targets, the majority of SLCs remains understudied. One major hurdle in research on SLCs is the lack of tools, such as cell-based assays to investigate their biological role and for drug discovery. Another challenge is the disperse and anecdotal information on assay strategies that are suitable for SLCs. This review provides a comprehensive overview of state-of-the-art cellular assay technologies for SLC research and discusses relevant SLC characteristics enabling the choice of an optimal assay technology. The Innovative Medicines Initiative consortium RESOLUTE intends to accelerate research on SLCs by providing the scientific community with high-quality reagents, assay technologies and data sets, and to ultimately unlock SLCs for drug discovery.

PAH induced remodelling with chamber-specific aspects. RAN prevented constitutive INaL enhancement and blunted myocardial remodelling. Partial mechanical unloading, resulting from an unexpected effect of RAN on pulmonary vasculature, might contribute to this effect.

Introduction: To assess the incidence of malignancy involvement of lymph nodes (LNs) in Marcille’s fossa in patients undergoing robot assisted radical prostatectomy (RARP) and extended pelvic lymph nodes dissection (ePLND) for prostate cancer (PCa). Design, Setting, and Participants: Between January 2014 and December 2017, details of patients who underwent RARP and ePLND were prospectively analysed. All the nodal packets were dissected separately, grouped into left and right nodes and submitted in separate packages to dedicated pathologist. Results and Limitations: Two hundred and twenty-one patients underwent ePLND and RARP in the study period. In aggregate, Marcille’s LNs involvement was found in 5 (2.3%) of patients, 2 on the left side and 3 on the right side. Per cent of positive cores and Gleason at biopsy are clinical predictors of LNs invasion; moreover, in the surgical specimen, seminal vesicle invasion and high-grade cancer were factors related to loco-regional metastases. Conclusions: Marcille’s nodes involvement is associated to contemporarily multiple LN metastases in other template locations in high-risk PCa patients. The Marcille’s lymphadenectomy would be recommended when planning an ePLND in high-risk PCa.

Until recently, the treatment of bladder cancer, for several years, was limited to surgery and to immunotherapy or chemotherapy. Currently, the extensive analysis of molecular alterations has led to novel treatment approaches. The advent of polymerase chain reaction and genomic hybridization techniques has allowed to investigate alterations involved in bladder cancer at DNA level. By this way, bladder cancers can be classified as papillary or non-papillary based on genetic alterations with activation or mutations in FGFR3 papillary tumors and with inactivation or mutations involving TP53 and RB1 in non-papillary tumors. Recently, the patterns of gene expression allow to differentiate basal and luminal subtypes as reported in breast cancer. In particular, basal cancers are composed of squamous and sarcomatoid pathological findings, while luminal cancers are composed of papillary finding features and genetic mutations (FGFR3). In particular, specific investigative studies demonstrated that luminal cancers are associated with secondary muscle invasive cancer while basal tumors are related to advanced disease since they are often metastatic at diagnosis. Moreover, from therapeutic point of view, different researchers showed that mutations of DNA are related to the sensitivity of bladder cancer while performing cisplatin chemotherapy. In this prospective, the bladder cancer molecular subtyping classification might allow identifying the set of patients who can safely avoid neoadjuvant chemotherapy likely because of the low response to systemic chemotherapy (chemoresistant tumors). In this context, the Cancer Genome Atlas (TCGA) project has improved the knowledge of the molecular targets of invasive urothelial cancers allowing the researchers to propose hypothesis suggesting that agents targeting the genomic alterations may be an effective strategy in managing these cancers, which occur in about 68% of muscle invasive cancers. A future goal will be to combine treatment strategies of invasive bladder cancers according to their genetic mutational load defined by molecular pathology.