RESUMEN
Since damage induced by ischemia-reperfusion (I/R) involves alterations in Ca2+ homeostasis and is reduced by ischemic postconditioning (IP) and that CoCl2 can trigger changes resembling the response to a hypoxic event in normoxia and its blockade on Ca2+ current in heart muscle, our aim was to evaluate CoCl2 as an IP therapeutic tool. Mechanic and energetic parameters of isolated and arterially perfused male Wistar rat heart ventricles were simultaneously analyzed in a model of I/R in which 0.23 mmol/L CoCl2 was introduced upon reperfusion and kept or withdrawn after 20 min or introduced after 20 min of reperfusion. The presence of CoCl2 did not affect diastolic pressure but increased post-ischemic contractile recovery, which peaked at 20 min and decreased at the end of reperfusion. This decrease was prevented when CoCl2 was removed at 20 min of reperfusion. Total heat release increased throughout reperfusion, while economy increased between 15 and 25 min. No effect was observed when CoCl2 was introduced at 20 min of reperfusion. In addition, both the area under the contracture curve evoked by 10 mmol/L caffeine-36 mmol/L Na+ and the contracture tension relaxation rate were higher with CoCl2.Furthermore, CoCl2 decreased the number of arrhythmias during reperfusion and the ventricular damaged area. The presence of CoCl2 in reperfusion induces cardioprotection consistent with the improvement in cellular calcium handling. The use of CoCl2 constitutes a potential cardioprotective tool of clinical relevance.
Asunto(s)
Contractura , Enfermedad de la Arteria Coronaria , Poscondicionamiento Isquémico , Daño por Reperfusión Miocárdica , Animales , Cobalto , Isquemia , Masculino , Reperfusión Miocárdica , Daño por Reperfusión Miocárdica/tratamiento farmacológico , Ratas , Ratas WistarRESUMEN
The layer-by-layer (LbL) method is based on sequential deposition of polycations and polyanions. Many of the properties of polyelectrolyte thin films deposited via this method depend on the nature of the topmost layer. Thus, these properties show odd-even oscillations during multilayer growth as the topmost layer alternates from polycations to polyanions. The work function of a (semi)conductive substrate modified with an LbL polyelectrolyte multilayer also displays an oscillatory behavior independent of film thickness. The topmost layer modulates the work function of a substrate buried well below the film. In agreement with previous observations, in this work, we show that the work function of a gold substrate changes periodically with the number of adsorbed layers, as different combinations of polycations and polyanions are deposited using the LbL method. For the first time, we rationalize this behavior in terms of formation of a dipole layer between the excess charge at the topmost layer and the charge of the metal substrate, and we put forward a semiquantitative model based on a continuum description of the electrostatics of the system that reproduces the experimental observations.