الملخص
Objective To observe the effect of KN93, a CaMK Ⅱ inhibitor, on delayed afterdepolarization (DAD) and calcium ion in ventricular myocytes of rabbits with heart failure, and to investigate the effect of CaMK Ⅱ signaling pathway on trigged arrhythmia after heart failure. Methods Thirty male New Zealand White rabbits were randomized(random number) into the sham operated group (sham group), heart failure group (HF group) and heart failure with KN93 group (HF+KN93 group) (n=10 each group). The rabbit heart failure model was established by abdominal aortic constriction combined with aortic valve regurgitation. The ventricular myocytes were isolated by double enzyme digestion. The action potential and the transient inward current (Iti) were recorded by the whole-cell patch-clamp. The intracellular calcium transient was measured by the ion concentration measurement system. The main calcium transporter protein was detected by Western blotting. Data were analyzed by pCLAMP10.2. Statistical analysis was performed using SPSS 17.0. Comparisons among groups were conducted using ANOVA, and SNK-q multiple comparison procedure was utilized for post-hoc analysis.Results (1) After induction of heart failure, DAD and increment of trigger activity (TA) were observedin rabbit ventricular myocytes. Treatment of KN93 with 1.0 μmol/L reduced the events of DAD and TA.(2) After induction of heart failure, Iti densities were increased from -0.12±0.02 pA/pF to -0.95±0.06pA/pF at the polarization potential of -50 mV (n=10, P<0.01). The current densities were reduced to -0.44±0.04 pA/pF after application of 1.0 μmol/L of KN93 (n=10, P<0.01). (3) KN93 led to decrementof intracellular calcium ion concentration and calcium transient amplitude, and acceleration of the decayprocess of calcium transient. (4) KN93 upregulated the expression of pPLN and SERCA2a, increased the uptake of intracellular calcium ion, downregulated the expression of NCX, decreased the Iti, and reduced the occurrence of DAD and TA. Conclusions KN93 can reduce the intracellular calcium ion concentration of the heart failure animal model, and the occurrence of the DAD and TA. CaMK Ⅱ may be a new therapeutic target for arrhythmias in the heart failure.
الملخص
Objective To explore the effects of bone marrow mesenchymal stem cells (MSCs) transplantation on receptor-interacting protein kinase 1 (RIP1) and RIP3 in rat brain after cardiac arrest (CA).Methods Sprague Dawley (SD) rats were randomly (random number) divided into sham group (n=8),CA group (n=8) and MSCs group (n=8).Animals were subjected to asphyxial cardiac arrest and followed by cardiopulmonary resuscitation (CPR).In MSCs group or CA group,animals received intravenous injection of 1 × 106 MSCs in 0.5 mL phosphate buffer solution (PBS) or 0.5 mL PBS alone at 1 h after successful resuscitation.Neurological deficit scores (NDS) were assessed at 3 d after CPR.Donor MSCs in brain were detected under a fluorescent microscope.HE staining of brain tissue was performed to observe necrotic neurons.Western blot analysis was performed to measure the levels of RIP1 and RIP3 in brain.Multiple comparisons were made by analysis of variance or Kruskal-Wallis H test.Results At 3 d after CPR,MSCs group demonstrated higher NDS than CA group [72.5(71.5,73.2) vs.63.0(62.5,64.1),Z=3.376,P=0.001].DAPI-labeled MSCs were primarily observed in the cerebral cortex.The percentage of necrotic neurons in MSCs group was significantly lower than that in CA group [(29.6±5.9)％ vs.(57.2±6.4)％,t=8.922,P＜0.01].The levels of RIP1 and RIP3 expression in brain in MSCs group were significantly lower than those in CA group [RIP1:0.227(0.193,0.243) vs.0.599(0.535,0.629),Z=3.151,P=0.001;RIP3:0.217(0.203,0.274) vs.0.543(0.533,0.555),Z=3.361,P=0.001].Conclusion MSCs transplantation improves neurological function after CPR from CA in rats likely associated with inhibiting necroptosis.
الملخص
Objective To observe the effect of allicin on the action potential duration (APD) and L-type calcium current (ICa,L) in the ventricular myocytes of rabbits with heart failure in order to explore the mechanisms of therapeutic effect of allicin on cardiac arrhythmias complicated with heart failure.Methods Forty-five New Zealand White male rabbits were randomly (random number) assigned to 3 groups (n=15 in each group):sham operated group (sham group),heart failure group (HF group),and heart failure treated with allicin group (HF+All group).The rabbit heart failure model was established by abdominal aortic constriction coupled with aortic regurgitation,the ventricular myocytes were obtained by enzyme double digestion,and the whole cell clamp was used to record action potential and calcium current.The action potential duration (APD),Ica,L and gating mechanism were observed during heart failure and allicin administered.Data were processed with pCLAMP version 10.2.Statistical analysis was performed using SPSS 17.0.Comparisons among groups were carried out using ANOVA,and SNK-q was used for multiple comparison as post-hoe.Results (1) Prolonged APD was found during heart failure,APD50 was prolonged from (93.4±4.7) ms in sham group to (115.5±6.2) ms in HF group(P＜0.01).After administration of allicin 30 μmol/L,APD50 was shortened to (105.2±5.5) ms (P＜0.05).(2) The density of ICa.L increased during heart failure,peak current density increased increased from (-8.4±0.6) pA/pF in sham group to (-15.1± 1.1) pA/pF while 0 mV attained at depolarizations (P＜0.01).After administration of allicin 30 μmol/L,the current density reduced to (-10.1+0.8) pA/pF (P＜0.01).The effect of allicin presented in both voltage dependent and consentration dependent manner.(3) According to the gating mechanism study,the main mechanism of lowering the density of ICa,L by allicin after heart failure was the acceleration of the steady inactivation of the channel,and the de-escalation of the recovery kinetic after the inactivation of the channel.Conclusions Allcin can be used to reduce the calcium current of ventricular myocytes in animal heart failure model,it has the potential of clinical use in treating cardiac arrhythmias during heart failure.