Objective To investigate whether increasing the concentration of serum potassium facilitates the cardioversion to sinus rhythm during cardiopulmonary resuscitation (CPR) in a rat ventricular fibrillation (VF) model. Methods Sprague-Dawley (SD) rats with sustained VF by electrical induction were randomized into two groups by random number table. Five minutes after onset of electrical induction, 2.5% potassium chloride solution at a dose of 0.8 mL/kg (KCl group, n = 9) or equivalent normal saline (NS group, n = 9) was given respectively via femoral vein followed by traditional CPR. The changes of electrocardiogram (ECG) and the effect of defibrillation were compared between the two groups. Results During the CPR, the number of animals with spontaneous cardioversion (2 vs. 1, P = 1.000) and successful defibrillation (7 vs. 3, P = 0.026) were both increasing in KCl group compare with those in the NS group, which required fewer defibrillation (1.60±0.79 vs. 2.70±0.58, P = 0.064), lower calculative defibrillation energy (J: 4.00±3.00 vs. 8.30±2.89, P = 0.068), more animals restore spontaneous circulation (ROSC, 9 vs. 4, P = 0.029) and shorter ROSC time (s: 265.10±134.58 vs. 421.30±162.06, P = 0.096). At the beginning of CPR, animals in two groups all presented the fine amplitude (amplitude < 0.5 mV). At CPR 3 minutes the KCl group presented significantly larger amplitude compared with NS group (mV: 0.92±0.16 vs. 0.67±0.23, P = 0.030); The amplitude decreased in the animals which did not attain cardioversion to sinus rhythm over time. The animal number of fine amplitude at CPR 7 minutes were 0 and 5, respectively, in the KCl group and the NS group. Conclusion Increasing serum potassium concentration facilitates the VF amplitude enlargement, promotes the spontaneous conversion, increases the successful rate of defibrillation and reduces the energy for defibrillation in a rat VF model.

Objective To study the effect of potassium chloride (KCl) before CPR on successful resuscitation of rats with ventricular fibrillation (VF).Methods Sprague-Dawley (SD) rats with VF induced by alternating electricity current were randomly (ramdam runmber) divided into KCl group and normal saline (NS) group.Rats of two groups were prepared with 0.8 mL/kg of 2.5％ KCl in KCI group and equivalent volume of NS in NS group instead before CPR.The resuscitation was considered to be failure if ROSC was absent for 10 min.The comparisons of time required for ROSC,the average attempt of defibrillation,the average joule used for defibrillation,ROSC rate and 72 h survival rate were carried out between the two groups.Results The length of time required for ROSC in the KCl group (n =10) was shorter than that in NS group (n=10) [(283.89±152.44) svs.(404.38±164.27) s] (t=1.369,P =0.196).The average attempt of defibrillation in KCl group were fewer compared to the NS group [(1.50 ± 0.75) times vs.(2.66 ± 0.57) times,(t =2.701,P =0.022)],the average joule used for defibrillation in KCl group were less compared to NS group [(3.75 ± 2.86) J vs.(8.33 ± 2.88) J,(t =2.78,P =0.019)].The ROSC rate in the KCl group was higher than that in NS group (P =0.011).The 72 h survival rate in KCl group was higher than that in NS group (P =0.001).Conclusions Increasing plasma potassium level before CPR could increase the ROSC rate and survival rate in rats with VF.

Objective:To explore the effect of extracellular signal-regulated kinase (ERK) inhibitor PD98059 on calpain-related proteins in the brain, and to understand the pathophysiological changes of calpain in cerebral ischemia/reperfusion injury (CIRI).Methods:Forty-two rats were divided into sham operation (Sham) group ( n = 6), model group ( n = 12), dimethyl sulfoxide (DMSO) control group ( n = 12), and PD98059 group ( n = 12) by random number table. The rat model of CIRI induced by cardiac arrest-cardiopulmonary resuscitation (CA-CPR) was reproduced by transesophageal electrical stimulation to induce ventricular fibrillation. In the Sham group, only the basic operations such as anesthesia, tracheal intubation, and arteriovenous catheterization were performed without CA-CPR. The rats in the DMSO control group and PD98059 group were injected with DMSO or PD98059 0.30 mg/kg via femoral vein, respectively, 30 minutes after the restoration of spontaneous circulation (ROSC), and rats in the Sham group and model group were given the same amount of normal saline. The duration of CPR, 24-hour survival rate and neurological deficit score (NDS) after ROSC were recorded. Hematoxylin-eosin (HE) staining and Nissl staining were used to observe the pathological changes of the cerebral cortex. The expressions of phosphorylated ERK (p-ERK), ERK, calpastatin, calpain-1, and calpain-2 were detected by Western blotting. The co-expression of p-ERK and calpain-2 was detected by double immunofluorescence. Results:There were no significant differences in the duration of CPR and 24-hour survival rate among all groups. In the model group, the nuclei of the cerebral cortex were obviously deformed and pyknotic, cells vacuoles and tissues were arranged disorderly, Nissl corpuscles were significantly reduced, NDS scores were also significantly reduced, level of ERK phosphorylation was increased, and calpain-2 protein was significantly up-regulated compared with the Sham group. There was no significant difference in the above parameters between the DMSO control group and the model group. After intervention with PD98059, the pathological injury of brain tissue was significantly improved, Nissl corpuscles were significantly increased, the NDS score was significantly higher than that in the model group [75.0 (72.0, 78.0) vs. 70.0 (65.0, 72.0), P < 0.05], the level of ERK phosphorylation and calpain-2 protein expression were significantly lower than those in the model group [p-ERK (p-ERK/ERK): 0.65±0.12 vs. 0.92±0.05, calpain-2 protein (calpain-2/GAPDH): 0.73±0.10 vs. 1.07±0.14, both P < 0.05], while there was no significant difference in the expressions of calpastatin and calpain-1 in the cerebral cortex among all the groups. Double immunofluorescence staining showed that p-ERK and calpain-2 were co-expressed in cytosol and nucleus, and the co-expression rate of p-ERK and calpain-2 in the model group was significantly higher than that in the Sham group [(38.6±4.3)% vs. (9.2±3.5)%, P < 0.05], while it was significantly lowered in the PD98059 group compared with the model group [(18.2±7.0)% vs. (38.6±4.3)%, P < 0.05]. Conclusions:ERK together with calpain-2 participated in CIRI induced by CA-CPR. PD98059 inhibited the expression of calpain-2 and ERK phosphorylation. Therefore, ERK/calpain-2 may be a novel therapeutic target for CIRI.