Browsing by Subject "Arrhythmias"

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    A sexy approach to pacemaking: differences in function and molecular make up of the sinoatrial node
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2019) Doris, Ursula; Kharche, Sanjay; Petkova, Maria; Borbas, Balint; Logantha, Sunil Jit R.J.; Fedorenko, Olga; Maczewski, MIchal; Mackiewicz, Urszula; Zhang, Yu; Chahal, Anwar; D’Souza, Alicia; Atkinson, Andrew J.; Dobrzynski, Halina; Yanni, Joseph
    Background. Functional properties of the sinoatrial node (SAN) are known to differ between sexes. Women have higher resting and intrinsic heart rates. Sex determines the risk of developing certain arrhythmias such as sick sinus syndrome, which occur more often in women. We believe that a major contributor to these differences is in gender specific ion channel expression. Methods. qPCR was used to compare ion channel gene expression in the SAN and right atrium (RA) between male and female rats. Histology, immunohistochemistry and signal intensity analysis were used to locate the SAN and determine abundance of ion channels. The effect of nifedipine on extracellular potential recording was used to determine differences in beating rate between sexes. Results. mRNAs for Ca v1.3, Kir3.1, and Nkx2-5, as well as expression of the L-Type Ca 2+ channel protein, were higher in the female SAN. Females had significantly higher intrinsic heart rates and the effect of nifedipine on isolated SAN preparations was significantly greater in male SAN. Computer modelling using a SAN cell model demonstrated a higher propensity of pacemaker-related arrhythmias in females. Conclusion. This study has identified key differences in the expression of Ca v 1.3, K ir 3.1 and Nkx2-5 at mRNA and/or protein levels between male and female SAN. Cav1.3 plays an important role in the pacemaker function of the SAN, therefore the higher intrinsic heart rate of the female SAN could be caused by the higher expression of Ca v 1.3. The differences identified in this study advance our understanding of sex differences in cardiac electrophysiology and arrhythmias.
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    Myocardial Connexin-43 and N-Cadherin decrease during vanadium inhalation
    (Universidad de Murcia. Departamento de Biología Celular e Histología, 2016) Fortoul, Teresa I.; Soto-Mota, Adrian; Rojas-Lemus, Marcela; Rodriguez-Lara, Vilaney; GonzalezVillalva, Adriana; Montaño, Luis F.; Paez, Araceli; Colin-Barenque, Laura; López-Valdez, Nelly; Cano Gutiérrez, Gumaro; Bizarro-Nevares, Patricia; Ustarroz-Cano, Martha
    Particulate matter air pollution has considerably increased during the last decades; vanadium is a transition element adhered to this particulate matter, and the combustion of fossil fuels is the main source in the atmosphere. It has been reported that air pollution and specifically vanadium exposure increases the probability of suffering arrhythmias; however the biological mechanism of such a relationship remains unknown. It has been established that a diminished presence of NCadherin alters the Connexin-43 arrangement, and the consequent altered presence of these proteins predisposes to ventricular heart rate problems. We analyzed myocardial histology and the expression of N-Cadherin and Connexin-43 by immunohistochemistry in mouse that inhaled vanadium. Our results showed a significant and progressive reduction in both N-Cadherin and Connexin-43, as well as the presence of meganucleus; myofibrils disruption, and clumping in the exposed groups were also observed. Our findings add more information about a possible explanation for the arrythmogenic effect observed in dwellers of cities with high particulate matter atmospheric pollution.