Inhibitory effect of aerobic exercise on left ventricular remodeling and sympathetic neural remodeling in rats with heart failure after myocardial infarction

AIM: To investigate the effects of long-term aerobic exercise on the heart and sympathetic neural remodeling (structure and function remodeling) in heart failure rats induced by myocardial infarction. METHODS: Heart failure model after myocardial infarction was performed by ligating anterior descending coronary artery in the Wistar rats. Four weeks after operation, the rats were randomly divided into sham operation sedentary (S) group, heart failure sedentary (H) group and heart failure exercise (HE) group. The animals in HE group underwent 10-week treadmill running, while those in S group and H group were sustained in a resting state. The cardiac structure and function including left ventricular internal diameter at diastole (LVIDd), left ventricular internal diameter at systole (LVIDs), left ventricular anterior wall diameter at diastole (LVAWDd), left ventricular anterior wall diameter at systole (LVAWDs), left ventricular posterior wall diameter at diastole (LVPWDd) and left ventricular posterior wall diameter at systole (LVPWDs), and cardiac function parameters including fractional shortening (FS) and left ventricular ejection fraction (LVEF) were measured by echocardiography. The myocardium was collected for histopathological observation with Masson staining, and the collagen volume fraction (CVF) was determined. The concentrations of norepinephrine (NE) in the myocardium and plasma were measured by high-pressure liquid chromatography. The frequency domain analysis was applied for determining the heart rate variability (HRV) via subcutaneous recording electrode involving total power (TP), normalized low power (LFn), normalized high power (HFn) and LF/HF ratio. The mRNA expression of collagen type I (Col-I), collagen type III (Col-III), atrial natriuretic factor (ANF), α-myosin heavy chain (α-MHC), β-myosin heavy chain (β-MHC), sarcoplasmic endoplasmic reticulum Ca²⁺-ATPase (SERCA2a) was detected by real-time PCR. The protein levels of nerve growth factor (NGF) and its receptor (TrkA), and tyrosine hydroxylase (TH) were measured by Western blotting. RESULTS: (1) Compared with S group, body weight (BW), LVIDd, FS, LVEF, TP, HFn, the mRNA expression of α-MHC and SERCA2a, and the protein levels of NGF, TrkA and TH decreased (P<0.05). Left ventricular weight (LVW), left ventricular mass index (LVMI), LVAWDd, LVAWDs, LVPWDd, LVPWDs, CVF, plasma and myocardial NE content, LFn, LF/HF, and the mRNA expression of ANF, β-MHC, Col-I and Col-III increased (P<0.05) in H group. (2) Compared with H group, LVW, LVMI, LVIDd, FS, LVEF, TP, HFn, the mRNA expression of α-MHC and SERCA2a, and the protein levels of NGF, TrkA and TH were raised (P<0.05), while CVF, plasma and myocardial NE content, LFn, LF/HF, and the mRNA expression of ANF, β-MHC, Col-I and Col-III decreased (P<0.05) in HE group. CONCLUSION: Long-term aerobic exercise training leads to inhibition of heart and sympathetic neural remodeling and improvement of cardiac function and autonomic modulation in the rats after myocardial infarction.     

Effect of Nao-re-qing oral liquid on cAMP content in hypothalamus and CSF,and AVP content in ventral septal area of endotoxin-induced febrile rabbits

AIM: To explore the mechanism of Nao-re-qing oral liquid (NRQ) decreasing endotoxin (ET)-induced fever in rabbits. METHODS: (1) The ET-induced fever model was established in rabbits. Febrile response of rabbits was observed. (2) The arginine vasopressin (AVP) content in the ventral septal area (VSA), and cAMP content in hypothalarmus (HP) and CSF were determined by radioimmunoassay.RESULTS: (1) In ET group, the maximal increment in body temperature (ΔT) [(1.80±0.16) ℃], 6 h thermal respone index (TRI₆)(11.31±0.20), the cAMP content in the HP [(1.35±0.21)nmol/g], the cAMP content in CSF [(66.69±1.82) nmol/L] and AVP content in the VSA [(30.80±9.59)ng/g ] were significantly higher than those in NRQ+ET group[ΔT(0.82±0.08) ℃, TRI₆(5.73±0.09), HP: cAMP(0.70±0.50)nmol/g, CSF: cAMP(56.86±1.34), AVP:(11.91±3.47)ng/g]( P<0.01). (2) The AVP content in VSA, and cAMP content in HP and CSF were separately paralleled with the fluctuation of body temperature (AVP: r=0.972, P<0.01; HP: cAMP r=0.899, P<0.05; CSF: cAMP r=0.991, P<0.01). CONCLUSION: The antipyretic action of NRQ may be due to inhibiting the increase in cAMP in HP and meanwhile promoting the release of AVP in VSA.     

Simple and effective method for monitoring ambulatory electrocardiogram in toads

AIM：To screen out a suitable lead for monitoring the ambulatory electrocardiogram (ECG) in unrestrained toad, and to investigate its practicability. METHODS：After subcutaneously implanting the electrodes in toads under anaesthesia, the ambulatory ECG of 5 leads were monitored with BL-420S data acquisition and analysis system, and the leads which could well express the waveform in ECG were screened out. The recovery process of the toads from the artificial hibernation within 6 h, the day-to-day stability of the heart rate (HR) and the heart rate variability (HRV) in 5 successive days of hibernation, and the HR and HRV after freeze-thawing process were monitored to determine its practicability. RESULTS：Two out of 5 leads showed better ECG waveforms. Compared with 6 h post hibernation, lowered HR at 0 h and 1 h was observed, and the standard deviation of normal R-R intervals (SDNN) was significantly increased (P<0.05 or P<0.01), but the HR and SDNN from 2 to 5 h showed no significant difference, suggesting that the cardiac function reached the steady state after 2 h recovery. The HR at 2 h and 4 h on day 4 and day 5 decreased significantly compared with that on day 1 (P<0.05 or P<0.01), followed with a significant increase in SDNN (P<0.05 or P<0.01), suggesting that the ECG remained stable within 3 d. The HR increased, while SDNN decreased significantly at 1 h and 12 h post-thawing compared with that at pre-freeze (P<0.05), indicating the damaged cardiac function after freeze-thawing process. CONCLUSION：The method of subcutaneously implanting electrodes is suitable for effectively monitoring the ambulatory ECG in toads.     

花后温度和湿度条件对台农1号杧坐果率的影响

为探索杧果坐果率与开花后温度和湿度条件的关系,以台农1号杧为试材,应用生物统计学方法计算分析了80个温度和湿度自变量与不同时期坐果率的相关关系。结果表明:(1)花后14d的坐果率受温度和湿度条件影响最大。(2)花后7d两性花坐果率与花后1～6d平均空气相对湿度呈显著直线线性负相关,与花后1～2d、1～4d、1～6d的平均最高温度、平均温度、平均最低温度、>10℃积温无显著相关关系。(3)花后14d坐果率与花后6～10d的平均最高温度、4～10d平均温度、2～10d平均最低温度、4～14d>10℃积温呈显著或极显著的直线相关;与花后1～14d平均最高温度、平均温度呈显著的多项式线性相关;与花后1～14d平均空气相对湿度呈极显著的直线线性负相关。(4)花后25d坐果率与花后1～10d的平均最高温度、平均温度、>10℃积温以及花后1～14d平均最高温度呈显著的多项式线性相关。(5)有利于花后14d坐果的花后4～14d的下限平均温度为20.6℃,最适温度为24.7℃。     

Quantitative perfusion parameters of dynamic contrast-enhanced magne-tic resonance imaging in patients with rectal cancer: estimation of the microvascular perfusion and permeability

AIM: To investigate the perfusion parameters using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in rectal cancer patients so as to explore its potential value in estimating the microvascular condition including perfusion and permeability. METHODS: The data of 38 rectal cancer patients examined with DCE-MRI was retrospectively analyzed. The perfusion parameters of carcinoma and normal rectal wall in each case were calculated, including volume transfer constant (K^trans), rate constant of back flux (K_ep), extravascular extracellular space fractional volume (V_e) and initial area under curve (iAUC). The mean values of tumor and normal rectal wall, mucinous and nonmucinous carcinoma, poorly and moderately-to-well differentiated carcinoma, case with or without lymph node metastasis were compared. RESULTS: All the parameters of rectal cancer were higher than normal rectal wall (P<0.01). No significant difference was found between poorly and moderately-to-well differentiated carcinoma in terms of K^trans, K_ep and V_e, neither was the case with or without lymph node metastasis. The cases with lymph node metastasis had lower iAUC than those without (P<0.05). CONCLUSION: Quantitative perfusion DCE-MRI answered the microvascular perfusion and permeability change of rectal cancer compared with normal rectal wall, besides it could be used to distinguish between mucinous and nonmucinous carcinoma, which demonstrated its value in the evaluation of rectal cancer. However, it should not be recommended to predict the degrees of tumor cell differentiation and lymph node metastasis just according to the perfusion parameters.     

热杀菌条件对NFC冬枣汁成分及抗氧化活性的影响研究

为了研究不同热杀菌条件对NFC冬枣汁理化性质、活性成分及抗氧化活性的影响,本文以冬枣为研究对象,设置了低温长时杀菌(75℃,5、10、15、20、25 min)和高温短时杀菌(90℃,0.25、0.50、0.75、1.00、1.50 min)两个处理,考察了NFC冬枣汁的可溶性固形物含量、pH值、总酸含量、VC含量、DPPH清除率、亚铁离子还原率等指标。研究结果表明,两种杀菌方式对NFC冬枣汁基本理化性质影响不显著(P>0.05)。相比于低温长时杀菌,高温短时杀菌的△E值更低,更能保持冬枣汁原有的色泽。两种杀菌处理后多酚、VC含量均显著降低(P<0.05),低温长时杀菌25 min后VC含量未检出,抗氧化活性也显著低于高温短时杀菌(P<0.05)。因此,通过对NFC冬枣汁品质变化的分析,发现高温短时杀菌能更好地保持原有的色泽和营养成分。     

The correlation of serum ghrelin level with the total BMC,LM and body weight in premenopausal women with different thyroid functional status

AIM: To investigate the relationship between serum ghrelin level and body composition including bone mineral content (BMC), fat mass(FM) & lean mass(LM) in premenopausal women with different thyroid functional status. METHODS: We measured the serum ghrelin levels by radioimmunoassay (RIA), the serum levels of free triiodothyronine (FT3), free thyroxine (FT4) and sensitive thyroid-stimulating hormone (sTSH) by chemiluminescene immune assay. The total body composition including total BMC, FM and LM was measured by dual-energy X-ray absorptiometry (DXA) in 71 premenopausal women with different thyroid functional status (33 hyperthyroidism, 18 hypothyroidism and 20 normal subjects). RESULTS: (1) The level of serum ghrelin in patients with hyperthyroidism was significantly lower than that in patients with hypothyroidism (P<0.01) and normal subjects (P<0.01), but the serum ghrelin level in patients with hypothyroidism patients was similar to that in normal subjects (P>0.05). The serum ghrelin level was correlated negatively with FT3 (r=-0.318, P<0.01) and FT4 (r=-0.350, P<0.01), simultaneously correlated positively with serum sTSH (r=0.281, P<0.05). (2) The serum ghrelin level in 71 premenopausal women with different thyroid functional status correlated positively with the total BMC (r=0. 284, P<0.05), the total LM (r=0.259, P<0.05), body weight （r=0.279, P<0.05）but there was not correlation with total FM (P>0.05). CONCLUSION: The serum ghrelin level in the premenopausal women with different thyroid functional status may correlate with the total BMC, LM and body weight.     

Regulating autonomic nerve system: a new field of anti-inflammatory therapy for cardiovascular diseases

The role of chronic inflammation and autonomic neuropathy in the crucial underlying process contributing to the initiation and the progression of various cardiovascular diseases is well established. It is well known that the immune system is innervated by the autonomic nervous system, and the inflammatory reaction and immune reaction are re-gulated by the autonomic nerve system. Vagus nerve depresses inflammatory reaction via cholinergic anti-inflammatory pathway(CAP), while sympathetic nervous system has bidirectional regulation of pro-inflammation and anti-inflammation, which are affected by several factors such as the concentration of neurotransmitters or types of receptors. In this paper, we reviewed different effects of CAP and sympathetic nervous system on cardiovascular inflammatory reaction. Activation of CAP and regaining normal sympathetic function will improve the chronic inflammation in the process of cardiovascular diseases. Low-toxic and selective α7nAchR agonist is expected to be applied in cardiovascular diseases to alleviate chronic inflammation.     

The effects of ciliary neurotrophic factor on rat sciatic nerve regeneration

AIM: To observe the effects of ciliary neurotrophic factor (CNTF) on rat sciatic nerve regeneration, and compare the similarities and differences of its effects with that of nerve growth factor (NGF). METHODS: Sciatic nerve impairment model was prepared by break-restoring rat sciatic nerve. After intramuscular injection of different doses of CNTF at the damaged nerve for 45 days, the latent period and conduction velocity of action potential were determined. RESULTS: Compared with model group, the latent periods of all the CNTF treatment groups were significantly shortened (P<0.01) and the conduction velocity became faster significantly (P<0.01). Additionally, the effect on latent period in middle and high CNTF dosage groups is not significantly different form that in NGF treatment group (P>0.05). However, the conduction velocity in CNTF high dosage group is significantly faster than that in NGF treatment group (P<0.01). CONCLUSION: The effect of CNTF on promoting the rat sciatic nerve regeneration is better than that of NGF.     

Effects of hypoxia on the expression of heparanase and invasiveness of SKOV3 ovarian cancer cell line

AIM: To evaluate the effects of hypoxia on the expression of heparanase and the invasiveness of SKOV3 ovarial carcinoma cell line. METHODS: SKOV3 cells were incubated at either normoxia (37 ℃, 5％CO2, 21％O2) or hypoxia (37 ℃, 5％CO2, 1％O2) condition for 12 h, 24 h and 36 h. RT-PCR and Western blotting were used to detect mRNA and the protein expressions of heparanase under different conditions. Cell invasiveness was measured by matrigel invasion assay. RESULTS: Compared to normoxia group, the heparanase mRNA expression level in hypoxia group was increased and in 12 h hypoxia group was the highest. The heparanase protein expression in hypoxia group was also significantly increased (P<0.01) and the expression of heparanase in hypoxia group was also different (P<0.05). Compared to normoxia group, the level of cell invasion was markedly increased in 12 h, 24 h and 36 h groups (P<0.05). During 12-36 h hypoxia period, the increase in hypoxia-induced invasiveness in SKOV3 cell line showed a time-dependent manner (P<0.05). Meanwhile, there was a positive correlation between the expression of HPA and the invasiveness of SKOV3 cells (r=0.8530, P<0.05). CONCLUSION: Invasion of SKOV3 cells in hypoxia condition correlates with heparanase level. Hypoxia plays an important role in the augmentation of the heparanase expression and the invasiveness of human ovarian cancer.     

A simple and effective auxiliary device for detection of physiologic function on isolated sciatic nerve and gastrocnemius in toads

AIM: To design a simple and effective auxiliary device for detection of the compound action potential (CAP) and the force on the isolated sciatic nerve and gastrocnemius in toads, and to investigate its practicability. METHODS: A simple "L" shape device (L tube), which was composed of a nerve chamber and an organ bath, was made for fixing the isolated sciatic nerve and gastrocnemius. After fixing, the sciatic CAP and the gastrocnemius force were detected by BL-420S data acquisition and analysis system. The specimens were radomly divided into control group, and the lidocaine nerve and muscle groups. The sciatic nerve or gastrocnemius of each lidocaine group was firstly treated with the corresponding concentration of lidocaine, and then washed out with Ringer's solution, and its reversible anesthetic action on nerve conduction and muscle force was analyzed to verify the practicability of the L tube device. RESULTS: The CAP and the force of the sciatic-gastrocnemius specimens were detected concurrently by fixing the specimens in the L tube, and the liquid in the nerve chamber and organ bath was changed easily. Compared with the control, lidocaine at 0.05 and 0.2 g/L significantly increased the sciatic threshold stimulus voltage and maximal stimulus voltage (P<0.05), prolonged the absolute refractory period (P<0.01), and slowed down the conduction velocity (P<0.01). Lidocaine at 1 g/L completely blocked the sciatic conduction. The rest tension of the gastrocnemius was increased, and the maximal twitch force was decreased significantly by 1 g/L lidocaine (P<0.01), but the threshold and maximal stimulus voltage did not show statistic difference. The parameters of the sicatic nerve and gastrocnemius completely or partially recovered to the control level after washing out.CONCLUSION: As an auxiliary device, L tube makes the detection of CAP and force on the isolated sciatic nerve and gastrocnemius in toads more conveniently.     

Effect of inhibiting mTOR signaling pathway on p-AKT1 molecule in lung of juvenile SD rats and its significance

AIM:To investigate the effect of inhibiting mammalian target of rapamycin (mTOR) signaling pathway on phosphorylated AKT1 (p-AKT1) during lung injury induced by hyperoxygen in juvenile SD rats and its significance. METHODS:The SD rats (3 weeks old, n=72) were randomly divided into air + saline group, hyperoxia + saline group, hyperoxia + OSI-027 group, and hyperoxia + rapamycin group (n=18 in each group). The animal model was constructed by continuous intervention with a 90% volume fraction of oxygen, and normal saline, OSI-027 and rapamycin were administered by intraperitoneal injection at 1, 3, 6, 8, 10 and 13 d of the observation period. At 3, 7 and 14 d, the changes of the body weight, wet/drg weight ratio (W/D), lung histopathology, alveolar septal width and lung injury score were measured, and immunohistochemistry and Western blot were used to detect the distribution and protein levels of phosphorylated S6K1 (p-S6K1) and p-AKT1 in the lung tissues. RESULTS:Compared with air group, the body weight of the rats in hyperoxia group was significantly decreased (P<0.05), the lung W/D was increased in the acute phase of lung injury (P<0.05), and the alveolar septal width and lung injury scores were significantly increased (P<0.05). The p-S6K1 positive cells in the lung tissues were increased (P<0.05), p-AKT1 positive cells were decreased (P<0.05), p-S6K1 protein was increased significantly (P<0.01), and p-AKT1 protein was decreased significantly (P<0.01). Compared with hyperoxia group, the lung tissue injury in hyperoxia + OSI-027 group was alleviated (P<0.05), p-S6K1 positive cells in the lung tissues was decreased (P<0.05), p-AKT1 positive cells was increased (P<0.05), p-S6K1 protein level was significantly decreased (P<0.05), and p-AKT1 protein level was increased (P<0.05). Hyperoxia+rapamycin further aggravated lung injury (P<0.05), p-S6K1 positive cells decreased (P<0.05), p-AKT1 positive cells increased (P<0.05), p-S6K1 protein levels decreased significantly (P<0.05), and p-AKT1 protein levels increased significantly (P<0.05). Compared with hyperoxia + rapamycin group, the lung tissue damage was alleviated in hyperoxia + OSI-027 group (P<0.05), p-AKT1 positive cells in the lung tissues were decreased (P<0.05), and p-AKT1 protein level was decreased (P<0.05). CONCLUSION:p-AKT1 may be involved in the development of hyperoxia-induced lung injury, and its regulation mechanism may be related to the mTOR signaling pathway. In hyperoxia-induced lung injury, the protein level of p-AKT1 is decreased, and mTOR inhibitors increase the p-AKT1 protein. However, only the mTORC1/2 dual inhibitor OSI-027 alleviates the hyperoxia-induced fibrosis in juvenile SD rats.     

Effect and mechanism of Qing-Kai-Ling on endotoxin-induced fever in rabbits

AIM:To explore the antipyretic mechanism of Qing Kai-Ling (QKL) injection on endotoxin (ET)-induced fever in rabbits.METHODS:Rabbit models of endotoxin (ET)-induced fever were duplicated. The rectal temperature was measured by digital thermograph. The cAMP and IL-1β content in the hypothalamus (HP), the cAMP content in the cerebrospinal fluid (CSF), and the arginine vasopressin (AVP) content in the ventral septal area (VSA) were determined by radioimmunoassay.RESULTS:① QKL had significant antipyretic effect on ET-induced fever(P<0.01), ② The production of IL-1β and cAMP in HP was significantly inhibited by QKL treatment (P<0.01), ③ QKL markedly decreased the cAMP content in the CSF and AVP content in the VSA(P<0.01).CONCLUSION:The antipyretic mechanisms of QKL are probably due to inhibiting the production of the endogenous pyrogen and central mediator of fever, and meanwhile stimulating the release of the antipyretic substances.     

Relationship between waist to hip ratio and static lung volumes in adults

AIM: The study is designed to probe for the relationship between waist to hip ratio(WHR)and static lung volumes of adults. METHODS: In July-October 2008, 1 307 healthy adults(372 males and 935 females)were selected in Heilongjiang province by means of questionnaire and physical examination. The height, weight, WHR, fat mass, percentage body fat and lung function were measured, and then grouped according to the standard of classification of WHR(central obesity male WHR ≥ 0.86, female ≥ 0.82)for analysis of the relationship between WHR and static lung volume. RESULTS: WHR was found, regardless of sex, to tend to go up with the increase in age and BMI(P<0.01), and both the fat mass and percentage body fat of the central obesity group were higher than those in the group with normal WHR(P<0.01). An independent negative correlation was found(P<0.05), also regardless of sex, between the WHR with expiratory reserve volume(ERV)in all these adults. ERV in central obesity group was lower than that in the group with normal WHR(P<0.05). Compared to the normal group, ERV in the central obesity group decreased by 11% for males and 8% for females(P<0.05). However, with regard to the relationship between WHR and VT, IC, MV, and VC, gender differences were found. For the males, a significant independent positive correlation was observed between WHR and IC(P<0.05), with IC of the central obesity group 6% higher than that in the group with normal WHR(P<0.05). For the females, significant independent positive correlation was found between WHR and MV(P<0.05), with the VT and MV of the central obesity group 7% and 6% higher(P<0.05), respectively, than that in the group with normal WHR. CONCLUSION: WHR is in an independent negative correlation with ERV. The elevation of WHR may play a role in the impairment of respiratory function. Its occurrence is accompanied by a rise of IC for the male and a rise of MV for the female. These changes in the two genders could be associated with the decrease in arterial oxygen tension caused by the decrease of ERV.     

Microvessel density and expression of vascular endothelial growth factor in glomeruli of diabetic mice

AIM: To investigate the relationship between microvessel density (MVD) and expression of vascular endothelial growth factor (VEGF) in glomeruli of diabetic mice. METHODS: Streptozotocin-induced diabetic mice as well as the control mice were involved in this study for 6 weeks. The body weight and blood glucose level of the mice in each group were weekly measured at certain time point. The morphological changes of the kidney were observed under light microscope, and the diameter, perimeter and area of the glomeruli were detected by an image analysis system. The expression of CD34 and VEGF in glomeruli was examined by immunohistochemistry method, and MVD and VEGF index were also calculated. RESULTS: In comparison with the control mice, the blood glucose level was significantly increased,and the body weight was decreased in diabetic mice(P<0.01). The diameter, perimeter and area of glomeruli in diabetic mice were significant greater than those in control mice (P<0.05). Increased expression of CD34 and VEGF in the glomeruli of diabetic mice was observed. Glomerular MVD of diabetic mice was significantly higher than that of the controls (P<0.01), and was positively correlated with the VEGF index (r=0.9979, P<0.05). CONCLUSION: VEGF may promote the angiogenesis in glomeruli of diabetic mice. The increase in VEGF expression may play a role in the pathogenesis of diabetic nephropathy.     

Changes of AC activity and content of cAMP in hypothalamus of rats with fever and hypothermia

AIM:To observe the changes of AC activity and content of cAMP at different time point in hypothalamus of rats with fever and hypothermia. METHODS:Radioisotope method was used to measure the enzymatic activity of AC and the content of cAMP. RESULTS:(1)The fresh yeast caused fever after making model 4 h(P＜0.01). AC activity reached a peak value 3 h after making model (P＜0.05), subsequently AC activity rapidly decreased and increased again over normal level (P＜0.01);The change of cAMP content was positively related to the body temperature. (2) Aminopyrine induced rat hypothermia state after making model 15 min (P＜0.05). AC activity rapidly weakened and cAMP content rapidly descended to the lowest value at making model 45 min, subsequently AC activity and cAMP content in hypothalamus gradually increased again to normal range. CONCLUSION:(1)In fever model, it might be an important cause of febrile response that AC induced increase in intracellular cAMP content; (2) In hypothermia model, the significant decrease of AC activity and cAMP content indicate that cAMP might play a role in keeping hypothermia.     

Non-contact mapping and frequency analysis of vagal-mediated atrial fibrillation

AIM: To explore the mechanism of the initiation and maintenance of vagal-mediated atrial fibrillation (AF) by non-contact mapping and frequency analysis of vagal-mediated atrial fibrillation in canine.METHODS: Atrial effective refractory period (AERP) and dispersion of AERP were measured in 8 canine during baseline and bilateral cervical vagal nerve stimulation (CVNS). Left atrium (LA) and right atrium (RA) electrical activity of AF was assessed by non-contact mapping and frequency analysis.RESULTS: Compared with baseline, CVNS attenuated left and right AERP, but only increased the dispersion of left AERP. During CVNS, AF was easily induced and maintained, repetitive organized activations rotated around a preferential route were only found in the LA, and dominant frequencies (DFs) from LA were higher than those of the RA ［(12.5±1.5)Hz vs (9.3±1.2)Hz, P<0.01］. After the cessation of CVNS, DFs of AF decreased in the LA and RA ［(9.2±0.5)Hz vs (8.5±0.6)Hz, P>0.05］, and AF was spontaneously terminated.CONCLUSION: The change of electrophysiological character, difference of activation pattern, and frequency gradient between the LA and RA suggest that the initiation and maintenance of vagal-mediated AF dependent on the LA.     

Effects of interleukin-10 on the calcineurin activity in cultured cardiac fibroblasts induced by arginine vasopressin

AIM: The purpose of the present study was to investigate the effect of interleukin-10 (IL-10) on the proliferation and calcineurin (CaN) activity in cultured cardiac fibroblasts (CFs) induced by arginine vasopressin (AVP).METHODS: The CFs of left ventricle in neonatal Sprague-Dawley rats were isolated and cultured by trypsin digestion and selective plating technique. Then the proliferation rates of cells were determined by using the MTT ［3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide］ assay (A490 value). Cell cycle distribution was determined with flowcytometry technique. The CaN activity was measured by ultra-violet spectrophotography.RESULTS: (1) MTT colorimetry showed that 10-7 mol/L AVP significantly increased A490 value of CFs in comparison with control group (P<0.01). IL-10 attenuated the A490 value of AVP group in a concentration dependent manner. The A490 value of the 10-8, 10-7, 10-6, 10-5 g/L IL-10+10-7 mol/L AVP groups was 0.201±0.007, 0.187±0.006, 0.173±0.010 and 0.157±0.029 respectively, all data significantly lower than those in the presence of AVP alone (P<0.05 or P<0.01). (2) The percentage of the cells in S stage and proliferation index were markedly increased in 10-7mol/L AVP group compared with the control (P<0.01, respectively). In the 10-6 g/L IL-10+10-7 mol/L AVP group, the percentage cells in S stage and proliferation index were significantly lower than those in AVP group (P<0.01, respectively). IL-10 itself had no effect on fibroblast proliferation, but reduced AVP-induced fibroblast proliferation. (3) There was a significantly increase in CaN activity in AVP group compared with control (P<0.01). In the 10-8, 10-7, 10-6 and 10-5 g/L IL-10＋10-7 mol/L AVP groups, the CaN activity was 3.22±0.04, 3.06±0.06, 2.53±0.04 and 2.22±0.04, respectively. IL-10 dose-dependently down-regulated the CaN activity induced by AVP (P<0.01, respectively). However, the CaN activity was still higher in IL-10+AVP group than that in control group (P<0.05 or P<0.01).CONCLUSION: Our data indicate that IL-10 regulates the CaN activity of CFs in the cell proliferation induced by AVP, suggesting that IL-10 plays a role in the regression of cardiac remodeling.