211 research outputs found
Simultaneous measurements of electrical coupling and action potential transfer in pairs of ventricular cardiomyocytes
No full textSpread and modulation of electrical activity in cardiac tissue requires intercellular transfer of current via gap junctions, specialised regions of densely packed ionic channels. Electrotonic interaction is determined not merely by intercellular electrical resistance (Rj) but rather by the interplay of Rj and sarcolemmal passive and active electrical properties (Zaniboni et al., Spitzer et al.). In this work we combined a well established protocol to measure Rj in cell pairs (Weingart e Maurer) with a stimulation protocol which allowed to simultaneously study parameters relative to action potential transfer during sequential stimulation. Current clamp experiments, performed on cardiomyocyte pairs held in double-patch configuration, allowed to simultaneously monitor, at a relatively high frequency (1 Hz), membrane resistance (Rm), resting potential (Vm), maximum depolarization rate (dv/dtmax) and time to peak of dv/dtmax in both cells as well as Rj. Spontaneous electrical uncoupling was observed in guinea pig cell pairs with little or no effect on action potential transfer. Pharmacological uncoupling with 40 μM β-glycyrrhetinic acid reached, in one case, a much higher level of Rj and dramatically increased time delay for action potential appearance. When only Rj was measured over a short time interval after approximately two minutes from cell-attachments, values of Rj ∼ 40 MΩ in rat cell pairs (n=20) and Rj ∼ 15 MΩ in guinea pig cell pairs (n=24) were obtained. The possibility of monitoring simultaneously active and intercellular/cellular passive electrical properties makes this protocol particularly suitable to study dynamic changes in Rj during action potential transfer
Séminaire :"Frontières, temporalités, matérialités au prisme de la santé"
No full textà la Vieille Charité, EHESS, 2ème étage, salle A 2 Rue de la Charité, 13002 Marseille Le deuxième jeudi de chaque mois (sauf mars et mai) De 10h à 13h La première séance aura lieu le Jeudi 9 Novembre. PROGRAMME 9 Novembre 2017 Introduction générale du séminaire par Francesca Sirna (CNRS – CNE), Sandrine Musso (AMU – CNE) et Carine Baxerres (IRD – MERIT) Thématique : Temporalités Christine Jakobsen (SKOK – Center for Women and Gender studies, Bergen) et Sandrine Musso (AMU - CNE) « Penser l’..
Arrhythmogenesis in cardiac hypertrophy. Rate dependent effects of hypertrophy on action potential repolarization in rat ventricular myocytes
No full textArrhythmogenesis in cardiac hypertrophy. Rate dependent effects of hypertrophy on action potential repolarization in rat ventricular myocytes.
No full textOne disease, different features: COVID-19 laboratory and radiological findings in three Italian patients
No full textSimultaneous measurements of electrical coupling and action potential transfer in pairs of ventricular cardiomyocytes
No full textSignificance of uteroplacental Doppler at midtrimester in patients with favourable obstetric history
No full textObjective: To reassess the usefulness of midtrimester uterine Doppler in low-risk multiparous women. Methods: We prospectively recruited low-risk pregnant women at 20-22 weeks attending our clinic. Among those, women with a favourable obstetric history (group A) were distinguished from nulliparous (group B) and of each group we measured uterine artery Doppler (pulsatility index (PI)). We evaluated the accuracy of uterine artery Doppler in the prediction of preeclampsia and small for gestational age (SGA) neonates. Results: Between January 2009 and October 2010, 382 women were included in the study of which 147 in group A and 235 in group B. Overall, 26/382 (6.8%) women presented preeclampsia and SGA occurred in 59/382 (15.4%) cases. In our population, at a 10% false positive rate (FPR) uterine artery Doppler showed a detection rate (DR) of 19.2% for preeclampsia and of 37.3% for SGA, with a higher sensitivity for SGA neonates delivered 34 weeks (87% vs. 29.4%). The univariable receiver operating characteristics (ROC) curve by uterine artery PI yielded a significant prediction only for SGA in nulliparous women (areas under the curve (AUC) of 0.70; 95% CI 0.60-0.79). Conclusions: Our data confirmed that midtrimester uterine artery Doppler is not an efficient strategy in anticipating the risk of pregnancy complications among low-risk multiparous wome
Cellular electrophysiological changes induced by hypertrophy in ventricular myocytes of rast stimulated at various frequencies
No full textAlterazioni elettrofisiologiche cellulari indotte dall'ipertrofia in miociti ventricolari di ratto stimolati a diverse frequenze
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