Effect of experimental acute necrotizing pancreatitis on sodium and L-type calcium current in rat cardiomyocytes

AIM: To study the effect of experimental acute necrotizing pancreatitis (ANP) on sodium and L-type calcium current in rat cardiomyocytes. METHODS: I_Na and I_Ca-L were recorded using whole cell patch-clamp techniques from left ventricular myocytes in ANP model established by retrograde injection of 3.5% sodium taurocholate 2.5 mL/kg into pancreatic duct. RESULTS: Peak I_Na current density (at -30 mV) was significantly reduced in ANP [(12.45±2.26)pA/pF,n=16] compared with sham [(25.32±3.31)pA/pF,n=14], P<0.01; I_Ca-L current density (at +10 mV) was also significantly reduced in ANP [(3.63±0.65)pA/pF,n=16] compared with sham [(5.46±1.03)pA/pF,n=12], P<0.05. CONCLUSIONS: There were changes in both I_Na and I_Ca-L in cardiomyocytes of ANP. These changes may underlie the altered excitability and abnormally short transmembrane action potentials and repolarization of cardiomyocytes, thus contributing to arrhymias in ANP.     

Effect of garlicin on sodium channel current in rat ventricular myocytes

AIM: To observe the effect of garlicin on sodium channel(I_Na) in isolated ventricular myocytes of rats. METHODS: The ventricular myocytes of rats were obtained by enzymatic dissociation and treated with different concentrations of garlicin. The change of I_Na was recorded by the technique of whole-cell patch clamp recording.RESULTS: Garlicin decreased the I_Na of isolated ventricular myocytes in a dose- and voltage-dependent manner. The current density was elevated to peak under the condition that the membrane voltage was -40 mV before treated with garlicin. The current density was decreased by 48% from peak after treated with 500 μmol/L garlicin . No significant change of the active curve with the use of garlicin was observed. The median inactive voltages of the inactive curves before and after garlicin treatment were (-88.61±9.60) mV and (-103.03±8.90) mV (P<0.01), respectively, and the slopes were -7.85±0.88 and -7.55±2.75 (P>0.05), respectively, indicating that garlicin made a shift to the negative direction. CONCLUSION: Garlicin treatment induced the current density-voltage curve of I_Na to shift up and significantly decreased the current density. The inactive curve of sodium channel moved to the left, while the current density was not decreased after treated with garlicin. Garlicin blocks sodium channel in its inactive state in a dose- and voltage-dependent manner.     

Alteration of transient outward potassium current in ventricular myocytes from 1-week and 2-month infarcted rabbit hearts

AIM: To study the current density of transient outward potassium current (I_to) in cells from the epicardial zone of the 1-week and 2-month infarcted rabbit heart. METHODS: Rabbits were infarcted by ligation of the left anterior descending coronary artery, 1 week as well as 2 months later, the single ventricular myocytes were isolated enzymatically from the infracted area of 1-week infracted rabbit heart (PMI-1 week) and 2-month infracted heart (PMI-2 months), region remote from the infracted zone of 2-month infracted heart (REM-2 months) and free wall of left ventricule from noninfarcted heart (CON). I_to was recorded using whole cell patch-clamp techniques. RESULTS: Membrane capacitance of myocytes in REM-2 months group was signifitantly larger than that in CON. I_tocurrent density (at +60 mV) was significantly reduced in PMI-1 week and PMI-2 months compared with CON , P＜0.01. Nevertheless, there was an significant increase in PMI-2M compared with PMI-1W, P＜0.05. I_to current density was also significantly decreased in REM-2 months compared with CON (P＜0.05), while there was an significant increase in REM-2 months compared with PMI-2 months, P＜0.05. CONCLUSION: The results indicated that the reduction and change of I_to in infarcted rabbit heart were heterogenous. These changes may underlie the abnormally long transmembrane action potentials of these arrhymogenic surviving ventricular fibers of the infarcted heart, thus contributing to reentrant arrhythmias in the infarcted heart. By 2 months after myocardial infarction, the depressed I_to of infracted area had returned to nearly normal, suggesting the presence of reverse remodeling.     

Effects of apelin-13 on transient sodium currents in rat ischemic ventricular myocardial cells

AIM：To investigate the effects of apelin on ventricular arrythmias and cardiac functions in rat Langendorff perfusion-simulated myocardial ischemia model by observing the changes of transient sodium currents (INa) in normal cells and the simulated ischemic cells in rat left ventricle. METHODS：Ventricular cells were enzymatically isolated by the Langendorff perfusion system. INa was recorded by the technique of whole-cell patch-clamp. Some elements in the extracellular fluid were changed to simulate the normal or ischemic status. Forty Wistar rats were divided into 4 groups：normal group, ischemic group, normal with apelin group and ischemic with apelin group. The effect of apelin-13 on INa was observed. The method of rat Langendorff perfusion was used to simulate the ischemic heart model. The ventricular arrhythmia scores and heart functional parameters were compared. The expression level of sodium channel protein,type V,alpha subunit (SCN5A) in ventricular ischemic cells was measured by Western blotting. RESULTS： Apelin-13 increased INa amplitude in both normal myocardial cells ［(-86±13） pA/pF］ and ischemic myocardial cells ［(-52±15） pA/pF］. The results of current-voltage curve analysis indicated that apelin-13 did not change the conduction velocity of INa in the 4 groups ［(3.2±0.2） pS/pF, （3.1±0.3） pS/pF,（2.9±0.1）pS/pF and （2.8±0.4） pS/pF,respectively, P>0.05］. The membrane potentials at 50% maximal activation in the 4 groups were （-21.9±0.6） mV, （-28.7±0.3） mV, （-30.5±0.7） mV and （-36.8±0.2） mV, respectively, and the slope of activation curves was 5.6±0.3, 5.1±0.4, 4.3±0.3 and 4.9±0.6 (P>0.05), respectively. No difference of ventricular arrhythmia scores between normal group and normal with apelin group, as well as between ischemic group and ischemic with apelin group was observed. LVEDP in normal with apelin group was lower than that in normal group.The dp/dtmax and dp/dtmin in normal with apelin group were higher than those in normal group. Apelin improved cardiac function parameters in the ischemic hearts. The expression of SCN5A was not affected by apelin (28.8±3.6, 29.4±4.1, 30.1±2.9 and 31.3±3.8,respectively,P>0.05). CONCLUSION：Apelin-13 changes the gating properties of sodium channel, enhances the peak INa and facilitates the opening of sodium channel without inducing ventricular arrhythmias. Apelin-13 has a positive inotropic effect on both normal and ischemic hearts.     

Characteristics of transient outward potassium current in repolarization 1 phase from the canine right ventricular mid-myocardial cells

AIM: To examine the electrophysiological characteristics of transient outward potassium current(Ito₁) in repolarization 1 phase from the canine right ventricular M cells. METHODS: By use of whole cell patch-clamp technique, we quantitatively researched the ionic intensity, density of Ito₁ and the notch magnitude of action potential in repolarization 1 phase. RESULTS: (1) The activating process of Ito₁ of canine right ventricular M cells presented evident voltage-dependency. Under the condition of 37℃, 5 000 ms, 0 mV and +70 mV, the average peak Ito₁ intensity of right ventricular M cell were (690±380) pA and (3 130±1 910) pA, respectively (P＜0.01). (2) The Ito₁ intensity of canine right ventricular M cell possessed obvious frequent dependency. Under the condition of 37℃,+70 mV, 500 ms and 5 000 ms, the average peak Ito₁ intensity were (1 690±830) pA,(3 130±1 910) pA, respectively(P＜0.01), corresponding to the increase of action potential "spike-dome" magnitude in repolarization 1 phase. CONCLUSION: Potent Ito₁ as well as the "spike-dome"-like action potential figure mediated by Ito₁ is one of the prominent electrophysiological characteristics of the canine right ventricular M cells.     

Cardiac IKs as repolarization reserve plays a role in gender difference of diabetic QT prolongation

AIM: To explore the basic ionic mechanisms underlying long-QT syndrome by observing the changes of slowly activating outward rectifying potassium current (I_Ks) and its proteins in abnormal QT prolongation in different genders of diabetic rabbits.METHODS: A single injection of pre-warmed (37 ℃) alloxan (140 mg/kg) was used to establish a rabbit model of insulin-dependent diabetes mellitus. Eight weeks after alloxan injection, the levels of blood glucose in the rabbits were monitored and standard lead II electrocardiogram was recorded. The myocardial cells were isolated from the ventricle of the rabbits via enzymatic digestion. Whole-cell patch clamp technique was performed to study the action potential duration (APD) and I_Ks. The changes of both KvLQT1 and mink proteins were detected by Western blotting analysis.RESULTS: The QT interval and APD were prolonged apparently both in male and female diabetic rabbits. The increased APD/QT-I of the male diabetic rabbits is more remarkable than that of the female. The I_Ks step current density of the male diabetic rabbits was decreased at test potentials ranging from+40 mV to+70 mV compared with that of the control animals (P<0.05), which was lowered from (3.08±0.67) pA/pF (n=17) to (1.27±0.20) pA/pF (n=16) at+70 mV. However, the I_Ks step current density of the female diabetic rabbits was increased at test potentials ranging from 0 mV to+70 mV compared with that of control group (P<0.05), which was increased from (1.56±0.20) pA/pF (n=13) to (3.65±0.50) pA/PF (n=14) at+70 mV. The expression of KvLQT1 and mink in male diabetic group decreased by 21.6% and 18.5%, respectively. However, the expression of KvLQT1 and mink in female diabetic group were increased by 42.3% and 20.5%, respectively.CONCLUSION: The I_Ks may be a protective factor in the early period of diabetic development in female rabbits. As a repolarization reserve, cardiac I_Ks is likely to restrict the effects of excessively slowing repolarization.     

Effects of different β-adrenergic receptors on cardiac systolic and diastolic functions in hypoxic stress rats

AIM:To explore the effects of different β-adrenergic receptors (β-AR) on the left and right ventricular systolic and diastolic functions in rats under acute hypoxic stress. METHODS:The healthy male SD rats were randomly divided into 4 groups (n=7):control group, non-selected β-AR blocker propranolol group, selected β₁-AR blocker atenolol group and selected β₂-AR blocker ICI 118,551 group, and then the rats were exposed to normoxia (20.9% O₂, 79.1% N₂) and hypoxia (15.0% O₂, 85.0% N₂) condition respectively at the altitude of 2 260 m (Xining, China). The heart rate (HR), the left ventricular systolic pressure (LVSP), the right ventricular systolic pressure (RVSP), and the maximum raise/decline rate of left and right ventricular pressure (±dp/dt_max) were monitored, and the arterial blood gas in normoxia and hypoxia condition were compared to explore the effect of β-AR on the left and right ventricular systolic and diastolic functions in acute hypoxic stress rats. RESULTS:Under normoxia condition, the LVSP, ±dp/dt_max of left ventricular were decreased in propranolol group, atenolol group and ICI 118,551 group, the RVSP and ±dp/dt_max of right ventricle were decreased in propranolol group and atenolol group (P<0.05). Under hypoxia condition, the PaO₂, LVSP, ±dp/dt_max of left ventricle were decreased in all groups compared with the normoxia group, and the ±dp/dt_max of right ventricle was increased in all groups (P<0.05), also the degree of index change in control group was more obvious than that in propranolol group and atenolol group. CONCLUSION:The activation of β₁-AR is an important compensatory regulation for heart function during hypoxic stress. However, the compensatory enhancement of right heart function under acute hypoxia condition which through tonogenic dilation is more significant for maintaining the normal circulating blood flow.     

Effect of breviscapin on INa channel current in isolated rat ventricular myocytes

AIM: To investigate the effects of breviscapine on INa channel in isolated rat ventricular myocytes. METHODS: Single cell of rat ventricular myocyte was isolated by enzymatic dissociation. The whole-cell patch-clamp recording technique was used to observe the change of INa channel current influenced by breviscapine. RESULTS: Breviscapine decreased the INa channel current in a dose-dependent and voltage-dependent manner in rat ventricular myocytes. The current-voltage curve was significantly decreased. Breviscapin at concentrations of 1, 3, 30, 100 mg/L respectively decreased INa current density, which were (7.98±0.60)%, (37.73±2.31)%, (65.58%±2.90)% and (88.09±5.60)%, respectively. INa was inhibited in a voltage-dependent manner, showing a significant attenuating effect at test potentials from -30 mV to 0. The INa inactivation curve was shifted to left and the activation curve was shifted to right. Breviscapine step down the recovery curve significantly. CONCLUSION: Breviscapine concentration-dependently decreased INa channel current in rat ventricular myocytes.     

Effects of hydrogen peroxide on sodium current in acutely isolated rat hippocampal CA1 neurons

AIM and METHODS: The effects of hydrogen peroxide on Na⁺ currents were studied in freshly dissociated rat hippocampal CA1 neurons using the whole-cell patch-clamp techinique. RESULTS: ①H₂O₂ caused a dose-dependent and voltage-dependent increase in the voltage-activated Na⁺ currents. The amplitudes of Na⁺ currents were increased (48.0±4.2)% and (88. 2±5. 1)% (n=10) by H₂O₂ at 10 μmol/L and 100 μmol/L, respectively. ②H₂O₂ (10 μmol/L) did not affect the activation process, but changed the inactivation process significantly. Before and after application of 10 μmol/L of H₂O₂, the half-inactivation voltage was (-64.58±1.22)mV and (-53.55±0.94)mV (n=10, P<0.01), but the slope factor was not changed. CONCLUSION: As a product of oxidation metabolism, H₂O₂ is related to some diseases in the central nervous system.     

Characteristics of morphology and left ventricular function in the mouse with myocarditis

AIM:To determine the relationship between microhistology and cardiac contractility in myocarditis animal model. METHODS: Setting up myocarditis animal model by injecting Coxsackivevirus B₃ (CVB₃) into mice, then observed myocardial morphological changes and measured left ventricular function of mice at the time of first three days and two weeks after injecting CVB₃. RESULTS:Subcellular structure (mitochondria) changed at the first three days after injecting CVB₃. The left ventricular pressure (LVP) and the rate of intraventricular pressure development (dp/dt) which is the index of reflecting cardiac contractility depressed in this stage (14.2±0.8) kPa and (273.1±10.0)kPa/s, respectively. There were (17.1±0.7)kPa and (359.8±9.3)kPa/s in normal mice, respectively (P＜0.01). Myocardial lesions were more severe during immune response stage-two weeks after injecting CVB₃, including myocardial inflammation and necrosis. LVP was (11.8±0.2)kPa and dp/dt was (209.5±6.1)kPa/s in immune response stage. There was significant difference between mice with myocarditis at early stage and at immune response stage (P＜0.01).CONCLUSIONS:The factor of causing the depression of cardiac contractility in early stage (virus-induced damage) is mainly change of subcellular structure. Mitochondria cannot provide energy as normal. There were more severe myocardial lesions in later stage (cell-mediated autoimmune response)than in early stage. The depression of cardiac contractility is a consequence of multifactor.     

Effects of simvastatin on transient outward potassium current in ventricular myocytes of normocholesterolemic rabbits suffering from ischemia and reperfusion

AIM: To investigate the effects of simvastatin on transient outward potassium current (Ito) in left ventricular myocytes of rabbit heart undergoing ischemia-reperfusion, so as to explore the cellular (ionic) mechanism of statin treatment for antiarrhythmia. METHODS: Forty-five rabbits were randomly divided into three groups: ischemic-reperfusion group (I-R), simvastatin intervention group (statin) and sham-operation control group (sham). Anesthetized rabbits were subjected to 30 min ischemia by ligation of the left anterior descending coronary artery and 60 min reperfusion after oral administration of simvastatin at dose of 5 mg·kg-1·d-1(statin group) or placebo (I-R group) for 3 d. Single ventricular myocytes were isolated enzymatically from the epicardial zone of the infracted region derived from the hearts in I-R, statin group and the same anatomy region in sham. Whole cell patch clamp technique was used to record Ito. Simultaneously, the level of serum cholesterol was examined. RESULTS: No significant difference in serum cholesterol concentration among three groups was observed. The Ito current density (at +60 mV) was significantly decreased in I-R ［(9.49 ±1.91) pA/pF, n=11］ compared with sham ［(17.41± 3.13) pA/pF, n=15, P＜0.01］ and statin ［(15.24 ± 2.41) pA/pF, n=11, P＜0.01］, although there was slight reduction in statin group compared with sham (P＜0.05). CONCLUSION: Ischemia-reperfusion induces significant down-regulation of Ito, which may underlie the altered electrical activity and prolong abnormal transmembrane action potential duration of the surviving ventricular myocytes. Pretreatment with simvastatin attenuates these changes without lowering the serum cholesterol level, suggesting that simvastatin may reverse this electrical remodeling, thus contributing to the ionic mechanism of statin treatment for antiarrhythmia.     

Effect of changing left ventricular afterload and isolated perfused rabbit heart on ventricular refractory period measured by subthreshold conditioning train stimulation

AIM: To study the effect of changing left ventricular afterload and isolated perfused rabbit heart on ventricular refractory period measured by subthreshold conditioning train stimulation (S_t). METHODS: Ventricular refractory period strength-interval relation was measured by S_t method under the condition of changing left ventricular afterload and eliminating action of nervous and body fluid. RESULTS: Reducing left ventricular afterload pro- longed ventricular refractory period measured by S_t method (P＜0.05, P＜0.01). and S_t (200 Hz,100 ms) and S_t (50 ms,100 Hz) caused maximal prolongation of ventricular refractory period (P＜0.05, P＜0.01). CONCLUSION: Changing left ventricular afterload and eliminating action of nervous and body fluid could cause alteration of characteristic of ventricular refractory period strength-interval relation measured by S_t method.     

Changes of potassium currents in rabbit ventricle with healed myocardial infarction

AIM: To elucidate the mechanism of arrhythmia in healed myocardial infarction (HMI), and to investigate the changes of action potential duration (APD),transient outward potassium current (I_to), delayed rectifier potassium current (I_K) and inward rectifier potassium current (I_K1) of left ventricular myocytes in noninfarcted zone of HMI. METHODS: 12 rabbits were randomly assigned in two groups: HMI group (thoracotomy and ligation of the circumflex coronary); sham-operated group (thoracotomy but no conorary ligation). 3 months after operation, whole cell patch clamp technique was used to record APD, I_to, I_K and I_K1 of ventricular myocytes in non-infarcted zone. RESULTS: Membrane capacitance was larger in HMI group than that in sham-operated group. Action potential duration was lengthened significantly in HMI group and early after depolarization (EAD) appeared in HMI group. The densities of I_to, I_K,tail and I_K1 were reduced significantly in HMI group (P<0.01), from (6.72±0.42) pA/pF, (1.54±0.13) pA/pF and (25.6±2.6) pA/pF in Sham-operated group to (4.03±0.33) pA/pF, (1.14±0.11) pA/pF and (17.6±2.3) pA/pF, respectively. CONCLUSION: The reduced densities of I_to, I_K,tail and I_K1 in ventricular myocytes of non-infarcted zone in HMI are responsible for the prolongation of APD and the presentation of EAD, which play important roles in the malignant arrhythmia of HMI.     

Characteristics of pacemaker current in aged rat atrial myocytes

AIM: To investigate the characteristics of pacemker current (I_f) of atrium myocytes in aged rats. METHODS: Aged SD rats (22-24 months) were used in the study. The single atrium myocytes were isolated. I_f current was recorded by the technique of whole-cell patch clamp. RESULTS: The densities of I_f increased markedly in aged rat atrium myocytes compared with that in the cells of young rats. At the test potential of-150 mV, the average amplitude of I_f was (382±23)pA and the current density was (3.2±0.4)pA/pF, while the average amplitude of I_f in control group was (86.9±8.4)pA and the current density was (0.9±0.1)pA/pF,P<0.01. I_f current was augmented at negative hyperpolarzing test potential. Time constants of activation in aged and control cells were (230.2±14.4)ms and (670.5±23.6)ms, respectively. Furthermore, steady state curves in the elder cells was shifted to positive potentials and the voltages for half maximal activation were (-87.2±2.3)mV (aged cells) and (-104.4±6.3)mV (control cells). In contrast, the slope of activation curves and reversed potential of I_f were slightly different between aged cells and control cells. CONCLUSION: The amplitude and densities of I_f in atrium cells of aged rats were larger than that of control rats.     

Effects of arachidonic acid on action potential and L-type calcium current in rabbit cardiomyocytes

AIM:To study the influence of arachidonic acid (AA) on the action potential and L-type calcium current in rabbit cardiomyocytes. METHODS:Single ventricular myocyte was isolated using enzyme dispersion method. Whole-cell clamp-patch technique was used to record action potential and L-type calcium current. RESULTS: ① AA shortened action potential duration obviously, without marked effect on the resting potential and action potential amplitude. ② AA reduced the current densities from (10.21±3.15)PA/PF to (6.53±2.17)PA/PF (n=6, P<0.05), and up-shifted the I-V curves of ICa-L without changes of their active, peak and reverse potentials. CONCLUSION:AA inhibits L-type calcium current and shortens action potential duration, which may contribute to its cardiovascular effect.     

The effect of glucose,lactate and pyruvate on the dynamic adaptation of cardiac mitochondrial oxygen consumption

AIM: To understand the effect of exogenous carbon substrate on the dynamic regulation of cardiac oxidative phosphorylation. METHODS: Method of mean response time measurement of the myocardial mitochondrial O₂ consumption (t_mito) was developed by van Beek. Glucose, lactate, or pyruvate as carbon substrate respectively for myocardial energy supply was perfused in isolated rabbit hearts with Tyrode solution at 37℃. RESULTS: When heart rate was stepped up from 120 to 140 and 220 (beat·min^-1) respectively the t_mito. We have measured was: (6.3±1.0)s and (7.4±0.9) s for glucose; (5.4±1.2) s and (7.0±0.9) s for lactate; (4.0±0.7)s and (6.5±0.6) s for pyruvate (two way ANOVA, P＜0.05, compared with lactate and glucose). CONCLUSION: The transport of reducing equivalent into the mitochondrial matrix might be a limitation factor of dynamic adaptation of cardiac mitochondrial oxidative phosphorylation during fast changes in ATP utilization.     

Effect of cGMP on voltage-gated potassium channel in pulmonary artery smooth muscle cells from rats exposed to chronic hypoxia

AIM: To investigate the effect of cGMP on voltage-gated potassium channel in pulmonary artery smooth muscle cells (PASMCs) from rats exposed to chronic hypoxia. METHODS: (1) Wistar rats were randomly divided into control group (group A) and chronic hypoxia group (group B). Then group B received hypoxia 8 hours per day for 4 consecutive weeks. (2) Single PASMC was obtained via acute enzyme separation method. (3) Conventional whole-cell patch clamp technique was used to record resting membrane potential (Em) and ion currents of voltage-gated potassium channel. The changes of ion currents of voltage-gated potassium channel before and after applying cGMP (1 mmol/L), an agonist of protein kinase G (PKG), and cGMP plus H-8 (1 mmol/L), an inhibitor of PKG were compared between two groups. RESULTS: The Em of group B were significantly lower than that of group A. The ion currents of voltage-gated potassium channel in group A and group B were all significantly inhibited by cGMP [control group: from (118.0±5.0) pA/pF to (89.9±16.5) pA/pF, n=6, P＜0.05;chronic hypoxia group: from (81.0±5.0) pA/pF to (56.8±9.1) pA/pF, n=6, P＜0.05]and these effects were reversed by H-8 [control group: from (119.2±10.3) pA/pF to (117.8±9.1) pA/pF, n=6, P＞0.05;chronic hypoxia group: from (96.8±6.2)　pA/pF to (98.0±2.2)　pA/pF, n=6, P＞0.05]. CONCLUSIONS: The currents of voltage-gated potassium channel was inhibited by chronic hypoxic. The inhibitory effect of cGMP on currents of voltage-gated potassium channel in PASMCs from both normal and chronic hypoxic rats may be probably through the phosphorylation of voltage-gated potassium channel.     

Effect of Jiere Xingshen Injection on cAMP,IL-1β content in hypothalamus of ET febrile rabbits

AIM: The effects of Jiere Xingshen(JRXS) Injection on cAMP, IL-1_β content in hypothalamus (HP) of endotoxin(ET)-induced feverish rabbits were studied. METHODS: The ET-induced fever model was established in rabbits and the cAMP content in hypothalamus (HP) and csf, IL-1_β content in HP were determined by radioimmunoassay following intravenous infusion of JRXS. RESULTS: In ET group, the ΔT[(0.40±0.11)℃], TRI₁(1.78±0.79), cAMP content in HP[(2.90±0.40)nmol/g], cAMP content in csf[(0.40±0.11)nmol/L)], IL-1_β content in HP[(6.08±0.79)ng/g] were higher than that of NS and JRXS+ET group (P＜0.01). In JRXS+ET group, the ΔT[(0.10±0.10)℃], TRI₁(0.36±0.64), cAMP content in HP[(1.37±0.27)nmol/g], cAMP content in csf[(14.4±3.69)nmol/L)], IL-1_β content in HP[(2.90±0.37)ng/g] were very close to that of NS group but lower than that of the ET group (P＜0.01);The cAMP content in HP and csf, IL-1_β content in HP paralleled with the fluctuation of temperature. CONCLUTION: JRXS Injection has significant inhibitory effect on ET-induced fever by inhibiting cAMP and IL-1_β production in hypothalamus.     

Effects of transplantation of adipose stromal vascular fraction on cardiac function in adriamycin-induced heart failure rats

AIM: To investigate the effects of transplantation of adipose stromal vascular fraction (SVF) on the cardiac function in adriamycin-induced heart failure rats. METHODS: SVF was isolated from adipose tissue of a Sprague-Dawley (SD) rat by collagenase digestion and marked with green fluorescent protein (GFP) in vitro. Twenty-eight SD rats were randomized into normal control group (n=8), adriamycin control group (n=10) and SVF treatment group (n=10). Adriamycin at dose of 15 mg/kg was intraperitoneally injected into the rats twice a week for 4 weeks to induce heart failure. SVF cells (05 mL, 1×107/L) were injected via penis vein, and PBS vehicle was injected into the control animals in the same way. Four weeks later, the cardiac function was determined by multichannel physiologic recorder via cardiac catheterization. SVF was demonstrated in the myocardium by frozen section fluorescence microscopy. The CD31 expression was determined by an immunohistochemical test. RESULTS: Compared with adriamycin control group, SVF transplantation increased left ventricular peak systolic pressure ［LVSP, （13565±21.58) mmHg vs (10558±2262) mmHg, P<005］, left ventricular pressure maximal rise rate ［+dp/dtmax, (4 81565±56624) mmHg/s vs (3 53550±46528) mmHg/s, P<005］, and left ventricular pressure maximal decline rate ［-dp/dtmax, (3 67756±46775) mmHg/s vs (2 73865±51251) mmHg/s, P<005］. The results of the CD31 immunohistochemical test showed that the nuclear staining and granule distribution were more uniform, and the number of blood vessels per visual field increased in SVF treatment group as compared with adriamycin control group (P<005). CONCLUSION: SVF transplantation improves the cardiac function in the rat model of heart failure, possibly and partly through the promotion of myocardial neovascularization.     

Changes of Ca2＋ activated potassium channels and cellular-proliferation in autogenous vein grafts

AIM: To investigate changes of Ca^2＋ activated potassium channels (K_Ca) in autogenous vein grafts. METHODS: The contraction of venous ring was measured by means of perfusion in vitro. The intimal proliferation and proliferation of cultured smooth muscle cells (vascular smooth muscle cells, VSMCs) were observed by the means of computerised image analysis and MTT method, respectively. Furthermore, whole cell mode of patch clamp was used to record K_Ca of VSMCs isolated from autogenous vein grafts. RESULTS: 1 week after transplantation there were no significant differences of contraction and intimal relative thickness between autogenous vein grafts and control. Contraction and intimal relative thickness of autogenous vein graft were significantly increased 2 weeks after transplantation (P＜0.05, n=8 vs control), and they were more enhanced 4 weeks after vein transplantation (P＜0.01, n=8 vs control). TEA (blocker of Ca^2＋ activated potassium channels) increased MTT A₄₉₀ value of VSMCs from femoral vein in a dose-dependent manner (P＜0.05, n=8). K_Ca current density was significantly attenuated in VSMCs from autogenous vein grafts 1-4 weeks after transplantation (P＜0.05, n=5). CONCLUSION: K_Ca was inhibited in autogenous vein graft, which accounted for vasospasm and intimal proliferation.