Browsing by Author "Velasco, Myrian"

Now showing 1 - 2 of 2
  • Artículo
    Metabolic syndrome remodels electrical activity of the sinoatrial node and produces arrhythmias in rats
    (2013-11-08) Albarado Ibañez, Alondra; Avelino Cruz, José Everardo; Velasco, Myrian; Torres Jácome, Julián; Hiriart, Marcia; Albarado Ibañez, Alondra; 0000-0002-4725-7714; Avelino Cruz, José Everardo; 0000-0001-9685-4710; Velasco, Myrian; 0000-0002-9276-1928
    "In the last ten years, the incidences of metabolic syndrome and supraventricular arrhythmias have greatly increased. The metabolic syndrome is a cluster of alterations, which include obesity, hypertension, hypertriglyceridemia, glucose intolerance and insulin resistance, that increase the risk of developing, among others, atrial and nodal arrhythmias. The aim of this study is to demonstrate that metabolic syndrome induces electrical remodeling of the sinus node and produces arrhythmias. We induced metabolic syndrome in 2-month-old male Wistar rats by administering 20% sucrose in the drinking water. Eight weeks later, the rats were anesthetized and the electrocardiogram was recorded, revealing the presence of arrhythmias only in treated rats. Using conventional microelectrode and voltage clamp techniques, we analyzed the electrical activity of the sinoatrial node. We observed that in the sinoatrial node of “metabolic syndrome rats”, compared to controls, the spontaneous firing of all cells decreased, while the slope of the diastolic depolarization increased only in latent pacemaker cells. Accordingly, the pacemaker currents If and Ist increased. Furthermore, histological analysis showed a large amount of fat surrounding nodal cardiomyocytes and a rise in the sympathetic innervation. Finally, Poincaré plot denoted irregularity in the R-R and P-P ECG intervals, in agreement with the variability of nodal firing potential recorded in metabolic syndrome rats".
  • Artículo
    Ventricular dysfunction in obese and nonobese rats with metabolic syndrome
    (2022-02-22) Torres Jacome, Julian; Ortiz Fuentes, Brian Sabino; López Silva, Benjamin; Velasco, Myrian; Ita Amador, Martha Lucia; Albarado Ibañez, Alondra; Torres Jacome, Julian; 0000-0002-8575-2839; Ortiz Fuentes, Brian Sabino; 0000-0002-3409-897X; Albarado Ibañez, Alondra; 0000-0002-4725-7714
    "Obesity and dyslipidemias are both signs of metabolic syndrome, usually associated with ventricular arrhythmias. Here, we tried to identify cardiac electrical alteration and biomarkers in nonobese rats with metabolic syndrome (MetS), and these findings might lead to more lethal arrhythmias than obese animals. The MetS model was developed in Wistar rats with high-sucrose diet (20%), and after twenty-eight weeks were obtained two subgroups: obese (OMetS) and nonobese (NOMetS). The electrocardiogram was used to measure the ventricular arrhythmias and changes in the heart rate variability. Also, we measured ventricular hypertrophy and its relationship with electrical activity alterations of both ventricles, using micro-electrode and voltage clamp techniques. Also, we observed alterations in the contraction force of ventricles where a transducer was used to record mechanical and electrical papillary muscle, simultaneously. Despite both subgroups presenting long QT syndrome (0.66 ± 0.05 and 0.66 ± 0.07 ms with respect to the control 0.55 ± 0.1 ms), the changes in the heart rate variability were present only in OMetS, while the NOMetS subgroup presented changes in QT interval variability (NOMetS SD = 1.8, SD2 = 2.8; SD1/SD2 = 0.75)".