苄阿米洛利和钌红对颈动脉窦压力感受器放电的阻断作用

目的研究苄阿米洛利、阿米洛利和钌红对颈动脉窦压力感受器放电的作用,探讨压力感受器上机械敏感通道的性质。方法制备家兔离体颈动脉窦-窦神经标本,采用颈动脉窦窦内外双重灌流,钳制窦内压并记录窦神经放电,观察上述药物对压力感受器放电的作用。结果苄阿米洛利以浓度依赖性方式阻断窦神经放电,IC50值为18.5μmol/L,该阻断作用在冲洗后能大部分消除;阿米洛利(2 mmol/L)可阻断95%的窦神经放电,其作用可逆;钌红(100μmol/L)以不可逆的方式抑制89%的窦神经放电活动。结论分属A类和C类纤维的压力感受器活动均可被阿米洛利类药物和钌红阻断,提示2类压力感受纤维末梢上有相似的机械敏感通道,但是有关的机械-电转导分子还有待进一步研究。     

硫化氢对家兔肠系膜动脉血管环张力调节研究

目的:观察硫化氢(H2S)对家兔肠系膜血管环张力的调节作用,及其可能的作用机制。方法:应用离体血管环张力测定技术,用金属钩将3mm左右的动脉环悬置于含K-H液的离体器官浴槽中,观察硫化氢在血管环张力的作用,由计算机生物信号采集处理系统进行记录分析,检测血管环张力的变化,制作浓度反应曲线。结果:(1)外源性的NaHS(H2S的供体)可以剂量依赖性地舒张由氯化钾(KCL)预收缩的肠系膜动脉血管环。(2)用ATP敏感性钾通道(KA T P)通道阻断剂格列苯脲(Gli)、钙通道的开放剂1,4-二氢-2,6-二甲基-5-硝基-4-(2-[三氟甲基]苯基)吡啶-3-羧酸甲酯(Bay K8644)、NO合酶的抑制剂左旋硝基精氨酸甲酯(L-NAME)和环氧合酶阻断剂吲哚美辛预处理以及去除血管内皮后,H2S的舒张效应均被显著抑制,浓度反应曲线均明显右移。(3)给予鸟苷酸环化酶的抑制剂1H-(1,2,4)恶二唑(4,3-α)喹喔啉-1-酮(ODQ)预处理后,对H2S的舒张作用没有显著改变。结论:H2S在50～800μmol/L之间浓度依赖性的舒张家兔肠系膜动脉,部分是通过开放KA T P通道和关闭L型钙通道实现的,但与3ˊ,5ˊ-环一磷酸鸟苷(cGMP)途径无关。此作用是内皮依赖性的,且与一氧化氮(NO)和前列环素(PGI2)具有协同作用。     

敏感硫电极法在测定心血管组织细胞及血浆胱硫醚-γ-裂解酶/硫化氢的应用

目的:建立测定微量硫化氢(Hydrogen sulfide, H2S)的敏感硫电极法.方法:根据硫化氢的理化特性,应用化学反应将溶液中物理溶解和化学形式存在的硫化氢转变成硫离子(S2-),应用敏感硫电极检测微量S2-,换算出溶液中H2S,构建了敏感硫电极检测H2S的方法.并检测了大鼠及人血浆中H2S的浓度、大鼠心血管组织中内源性H2S的含量以及大鼠心血管组织和细胞胱硫醚-γ-裂解酶(cystathionine-γ-lyase, CSE)的活性.结果:敏感硫电极检测1～80 μmol/L的S2-有较好的指数相关关系,应用该方法检测到雄性和雌性大鼠血浆H2S的浓度分别为(40±4)和(41±5) μmol/L,差异无统计学意义,人类男性和女性静脉血血浆H2S浓度分别为(33±4) μmol/L 和(35±5) μmol/L,差异无统计学意义.雌、雄大鼠主动脉组织H2S的含量分别为每毫克蛋白(24±6)和(25±5) nmol,心肌组织含量分别为每毫克蛋白(19±4) 和(19±6) nmol,差异无统计学意义.采用敏感硫电极法测量主动脉组织CSE活性与传统方法测量结果差异无统计学意义,但可精确测量出血管平滑肌细胞CSE的活性.结论:敏感硫电极法可以应用于CSE/H2S信号通路的检测.     

儿童青少年血浆新型气体信号分子硫化氢的参考值

目的 测定儿童与青少年血浆硫化氢含量的参考值.方法 健康儿童青少年200名,按照其年龄与性别分组,7～14岁75名(男43名,女32名),15～19岁125名(男64名,女61名),应用敏感硫电极法测定血浆硫化氢(H2S)含量.结果 学龄期7～14岁男孩血浆H2S含量为(52.2181±17.9400)μmol/L,女孩H2S含量为(51.9441±16.5448)μmol/L;15～19岁男孩血浆H2 S含量为(52.8771±14.1444)μmol/L,女孩H2 S含量为(53.6551±14.5563)μmol/L.各年龄组间及性别间差异均无显著性(P＞0.05),合并统计后得出儿童青少年血浆H2S含量的浓度均值为(52.8234±15.4339)μmol/L.结论 儿童青少年血浆H2S含量参考值为(52.8234±15.4339)μmol/L.     

钩藤碱抑制麻醉大鼠颈动脉窦压力感受性反射的研究

目的 研究钩藤碱(Rhy)对颈动脉窦压力感受性反射(CSB)的作用并探讨其作用机制.方法 利用隔离灌流大鼠颈动脉窦技术,确定各项功能参数,如阈压(TP)、饱和压(SP)、平衡压(EP)、工作范围(OR)、最大斜率(PS)和平均动脉压反射性下降幅度(RD)等.Rhy(10、50、100 μmol/L)溶于K-H液后灌流窦区,以斜坡方式升降窦内压来观察Rhy对CSB的影响.分别预先灌流一氧化氮合酶抑制剂L-NAME,钾通道阻断剂四乙铵(TEA)和L-型钙通道开放剂Bay K8644后再给予Rhy,观察它们对Rhy作用的影响.结果 Rhy浓度依赖性地抑制了CSB, 使其各功能参数改变, TP和SP增大,PS和RD均减小.Rhy的抑制作用不能被L-NAME(300 μmol/L)和 TEA(1 mmol/L)预处理所取消,而可被Bay K8644 (500 nmol/L)明显减弱.结论 Rhy抑制了CSB,此作用可能是通过减弱压力感受器的牵张敏感性离子通道的钙内流来实现,而与NO和钾通道无关.     

Cardioprotective effects of mitochondrial KATP channels activated at different time

Backgroud Recent studies in adult hearts have indicated that KATP channels in the inner mitochondrial membrance are responsible for the protection. And we investigated whether opening of mitochondrial KATP channels (mKATP) could provide myocardial protection for immature rabbits and determined its role in cardioprotection.Methods Thirty-four 3-4-week-old rabbits, weighing 300-350 g, were divided randomly into five groups: Group Ⅰ (control group, n=8); Group Ⅱ ［diazoxide preconditioning group; n=8; the hearts were pretreated with 100 μmol/L diazoxide for 5 minutes followed by 10-minute wash out with Krebs-Henseleit buffer (KHB)］; Group Ⅲ ［diazoxide+5-hydroxydeconate (5-HD) preconditioning group; n=5; the hearts were pretreated with 100 μmol/L diazoxide and 100 μmol/L 5-HD); Group Ⅳ (diazoxide+cardioplegia group; n=8; cardioplegia containing 100 μmol/L diazoxide perfused the hearts for 5 minutes before ischemia); Group Ⅴ (diazoxide+5-HD+cardioplegia group; n=5; the cardioplegia contained 100 μmol/L diazoxide and 100 μmol/L 5-HD). All hearts were excised and connected to langendrff perfusion system and passively perfused with KHB at 38℃ under a pressure of 70 cmH2O. After reperfusion, the recovery rate of left ventricular diastolic pressure (LVDP), ±dp/dtmax, coronary flow (CF), the creatinine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST) in coronary sinus venous effluent and the tissue ATP were measured. Mitochondria were evaluated semiquantitatively by morphology.Results After ischemia and reperfusion (I/R), the two groups that were treated by diazoxide only (Groups Ⅱ and Ⅳ) had a significant improvement in LVDP, ±dp/dtmax, and CF recovery. AST, LDH, and CK were decreased, and the levels of tissue ATP in the two groups were higher. Mitochondria was protected better in Group Ⅳ than in other groups. Conclusions Activating mKATP channels before and during ischemia can similarly protect immature rabbit hearts, and the mechanism is related to the direct protective effect on mitochondria. Opening of mKATP channel during ischemia provides a better protection for mitochondria than it does before ischemia.     

冠心病患者血浆中新型气体信号分子硫化氢的变化

OBJECTIVE: To investigate the changes of plasma hydrogen sulfide (H(2)S) in patients with coronary heart disease (CHD). METHODS: Plasma H(2)S levels were measured in 40 patients with CHD and 17 angiographically normal patients by sulfide-sensitive electrodes, and the variation of plasma H(2)S levels was analyzed in different clinical types of CHD and in different types of coronary artery lesions. The association of plasma H(2)S levels with the risk factors of CHD was also analyzed. RESULTS: Plasma H(2)S levels were significantly lowered in CHD patients in comparison with that in angiographically normal control subjects (26.10+/-14.27 micromol/L vs 51.74+/-11.94 micromol/L, P<0.001). In CHD patients, plasma H(2)S levels in unstable angina patients (UAP, 23.60+/-14.41 micromol/L) and acute myocardial infarction patients (AMI, 19.98+/-7.516 micromol/L) were significantly lower than that in stable angina patients (SAP, 38.41+/-14.53 micromol/L, P<0.05). No significant difference in plasma H(2)S levels was found between CHD patients with double-vessel and multi-vessel lesions (16.91+/-7.98 vs 18.39+/-7.78 micromol/L, P>0.05), but the two groups of patients had significantly lower plasma H(2)S levels than patients with single-vessel involvement (33.04+/-15.01 micromol/L, P<0.05 and P<0.01, respectively). Plasma H(2)S level was significantly lower in CHD patients with coronary artery occlusion than in patients with simple stenosis (19.04+/-9.55 vs 28.24+/-14.85 micromol/L, P<0.05). Among the CHD patients, H(2)S levels were significantly lower in smokers than in non-smokers (27.54+/-10.37 vs 32.24+/-15.77 micromol/L, P<0.05), also lower in hypertensive patients than in normotensive patients (20.36+/-8.69 vs 33.77+/-15.86 micromol/L, P<0.01). Plasma H(2)S levels showed a significant inverse correlation with blood glucose (r=-0.493 6, P=0.001 6), but there were no significant correlations with sex, age, cholesterol, triglyeride, TC, low-density lipoprotein, high-density lipoprotein, or body mass index. CONCLUSION: Decreased plasma H(2)S levels may correlate with the severity of CHD and changes of the coronary artery, and may implicate the risk factors of CHD such as smoking, hypertension, and high blood glucose.     

前列腺素对高胆固醇血症兔动脉压力感受器活动的影响

孤离一侧颈动脉窦，记录窦神经放电，研究前列腺素对高胆固醇血症兔动脉压力感受器活动的影响。结果表明：（１）环加氧酶抑制剂消炎痛使正常动物压力感受器活动明显减弱，而对高胆固醇血症动物却无明显作用，提示内源性前列腺素可增强正常动物压力感受器活动，而在高胆固醇血症动物，这种功能受损；（２）与正常动物相同，外源性前列环素（ＰＧＩ２）也使高胆固醇血症动物压力感受器活动明显增强，提示高胆固醇血症动物压力感受器对前列腺素的反应性仍保持正常，内源性前列腺素对该动物压力感受器活动无明显影响，这可能主要是内源性前列腺素缺乏所致。     

钾通道参与高铁血红素诱导的心肌保护作用

目的:研究血红素氧化酶1的诱导剂高铁血红素在对抗大鼠心肌缺血-复灌损伤中的作用及其相应机制。方法:利用离体大鼠心脏Langendorff灌流模型,观察心功能、心肌梗死面积等指标的变化。结果:腹腔注射高铁血红素后24 h,可明显改善缺血-复灌心脏(30 m in缺血/2 h复灌)的收缩功能,减少复灌期乳酸脱氢酶(LDH)和肌酸磷酸(CK)的释放,缩小心肌梗死面积。在腹腔注射高铁血红素前给予线粒体KATP通道阻断剂5-HD或肌膜KATP通道阻断剂HMR-1098均可取消高铁血红素引发的心肌保护作用。在高铁血红素预处理后24 h,缺血/复灌前10 m in给予K ca通道阻断剂pax illine,与高铁血红素组相比,心肌梗死面积扩大,心脏收缩功能下降。结论:高铁血红素预处理可对抗心肌缺血-复灌性损伤,其作用可能与激活KATP通道和K ca通道有关。     

外源性一氧化碳分子释放剂CORM-2对抗大鼠离体心脏缺血复灌损伤及其作用机制

目的:研究外源性一氧化碳(carbon monoxide,CO)对大鼠离体心脏缺血复灌的作用及其机制。方法:采用Langendoff离体心脏灌流模型,用结扎心脏冠脉前降支30min造成心肌缺血,松开结扎120min作为再灌。观察心脏收缩功能、心肌酶学和心肌梗死面积等指标。结果:25μmol/LCORM-2(外源性CO释放剂)显著改善了离体心脏缺血复灌时心功能的损伤,降低了乳酸脱氢酶(LDH)、磷酸肌酸激酶(CK)的释放,减少了梗死面积,但对冠脉流量的影响不大。10μmol/LCORM-2可减少LDH、CK和心肌梗死面积,但对心功能的影响不明显;而100μmol/L CORM-2却可增加缺血复灌心肌LDH的释放,加重心功能的损害。可溶性鸟苷酸环化酶抑制剂亚甲蓝、一氧化氮合酶(NOS)抑制剂L-NAME、线粒体ATP依赖性钾离子通道阻断剂(mitoKATP)5-HD和血红素氧化酶-1(HO-1)抑制剂Znpp均可不同程度地阻断25μmol/L CORM-2缩小缺血心肌梗死面积的作用。L-NAME和Znpp可阻断CORM-2降低LVEDP的作用,但是CORM-2增高LVDP和 dp/dt的作用仅被亚甲蓝和L-NAME所取消。结论:外源性一氧化碳对大鼠缺血复灌心脏有保护作用,其作用机制可能是通过NOS-cGMP和HO-1途径,激活线粒体ATP依赖性钾离子通道起作用的。     

二氧化硫衍生物舒张大鼠离体主动脉血管环的效应及其机制研究

目的:探讨二氧化硫(sulfur dioxide, SO2)及其衍生物的舒张血管作用及其机制.方法:离体大鼠主动脉环灌流,应用去甲肾上腺素(noradrenaline, NE)预收缩主动脉环后,观察其对SO2供体--亚硫酸钠/亚硫酸氢钠混合液(Na2SO3/NaHSO3, 3:1物质的量比)的舒张反应;观察应用KATP通道阻断剂格列本脲和钙通道阻断剂尼卡地平对Na2SO3/NaHSO3血管效应的影响;观察应用内源性SO2生成酶抑制剂天冬氨酸异羟肟酸(hydroxamate,HDX)和Na2SO3/NaHSO3预孵育血管组织后NE缩血管效应的变化.结果:大鼠离体主动脉环对Na2SO3/NaHSO3呈浓度(0～12 mmol/L)依赖性的舒张反应,IC50值为(7.28±0.12) mmol/L,最大舒张率(Emax)为78.79%±3.24%.格列本脲(1×10^-6 mol/L)抑制低浓度Na2SO3/NaHSO3(≤4 mmol/L)的舒血管效应,而对高浓度(＞6 mmol/L)的舒血管效应无明显影响.经尼卡地平(1×10^-9 mol/L)预孵育的血管环对NE的收缩反应明显减弱,Na2SO3/NaHSO3则不能舒张该血管.反之,预先用HDX(1×10^-4 mol/L)孵育阻断内源性SO2生成后,血管环对NE的收缩反应增强[EC50从(6.48±0.84)×10^-7 mol/L降至(3.97±1.63)×10^-7 mol/L,P＜0.01];而用Na2SO3/NaHSO3预先孵育的血管对NE的收缩反应曲线右移[EC50从(6.48±0.84)×10^-7 mol/L升至(4.93±0.81)×10^-5 mol/L,P＜0.01].结论:SO2具有明显的舒张血管平滑肌作用,其作用机制与钙离子通道及KATP通道有关,推测机体内源性SO2具有血管功能调节意义.     

EFFECTS OF GLIBENCLAMIDE, GLIMEPIRIDE, AND GLICLAZIDE ON ISCHEMIC PRECONDITIONING IN RAT HEART

Objective To compare the influence of different sulfonylureas on the myocardial protection effect of ischemic preconditioning (IPC) in isolated rat hearts, and ATP-sensitive potassium channel current (IKATP) of rat ventricular myocytes. Methods Isolated Langendorff perfused rat hearts were randomly assigned to five groups: (1) control group, (2) IPC group, (3) IPC glibenclamide (GLB, 10 μmol/L) group, (4) IPC glimepiride (GLM, 10 μmol/L) group, (5) IPC gliclazide (GLC, 50 μmol/L) group. IPC was defined as 3 cycles of 5-minute zero-flow global ischemia followed by 5-minute reperfusion. The haemodynamic parameters and the infarct size of each isolated heart were recorded. And the sarcolemmal IKATP of dissociated ventricular myocytes reperfused with 10 μmol/L GLB, 1 μmol/L GLM, and 1 μmol/L GLC was recorded with single-pipette whole-cell voltage clamp under simulated ischemic condition. Results The infarct sizes of rat hearts in IPC (23.7%±1.3%), IPC GLM (24.6%±1.0%), and IPC GLC (33.1%±1.3%) groups were all significantly smaller than that in control group (43.3%±1.8%; P<0.01, n=6). The infarct size of rat hearts in IPC GLB group (40.4%±1.4%) was significantly larger than that in IPC group (P<0.01, n=6). Under simulated ischemic condition, GLB (10 μmol/L) decreased IKATP from 20.65±7.80 to 9.09±0.10 pA/pF (P<0.01, n=6), GLM (1 μmol/L) did not significantly inhibit IKATP (n=6), and GLC (1 μmol/L) decreased IKATP from 16.73±0.97 to 11.18±3.56 pA/pF(P<0.05, n=6). Conclusions GLM has less effect on myocardial protection of IPC than GLB and GLC. Blockage of sarcolemmal ATP-sensitive potassium channels in myocardium might play an important role in diminishing IPC-induced protection of GLM, GLB, and GLC.     

加压素在家兔压力感受性反射中的作用

采用电刺激神经及牵拉颈动脉窦的方法兴奋压力感受器,观察了压力感受器兴奋时家兔某些脑区内及血浆中加压素含量的改变,以探讨其在压力感受性反射中的作用。结果表明:①电刺激减压神经产生明显减压效应时,家兔下丘脑、孤束核、垂体及血浆中加压素含量明显减少;②牵拉颈动脉窦时,家兔下丘脑、孤束核、垂体、脊髓及血浆中加压素含量明显减少,而延脑加压素含量显著增加。提示内源性加压素可能参与压力感受性反射调节过程。     

铁对白细胞介素-2舒血管效应的调制作用

目的 :研究微量元素铁对白细胞介素 - 2 (IL- 2 )舒血管效应的调制作用及其机理。方法 :采用离体主动脉环灌流模型 ,在苯肾上腺素 (1μmol/ L)预收缩基础上 ,测定经柠檬酸铁胺 (FAC)处理后 IL- 2对血管张力的变化 ;用分光光度法测定血管一氧化氮合酶 (NOS)活性。结果 :FAC(0 .1～ 10μmol/ L )孵育 30 min后对血管的张力无影响 ,却能浓度依赖性的抑制 IL - 2 (1～ 10 0 0 U/ ml)的舒血管效应 (P<0 .0 5～ 0 .0 1)。 IL - 2 (1、10、10 0、10 0 0 U/ ml)单独作用后的血管张力分别为加药前的 (78.4 7± 4 .31) %、(6 6 .86± 5 .5 5 ) %、(5 2 .6 2± 4 .5 1) %和 (4 2 .39± 4 .2 7) %。10 μmol/ L FAC预处理后再加 IL- 2 ,血管张力为 (89.81± 1.94 ) %、(86 .13± 3.11) %、(77.16± 5 .6 6 ) %和 (6 8.76± 5 .6 9) %。L-精氨酸 (1mmol/ L)孵育取消了 FAC对 IL- 2舒血管效应的抑制作用。IL- 2 (10 0 0 U/ ml)使 NOS的活性从 (9.86± 0 .5 4) U/ ml prot显著增高为 (2 2 .10± 1.87) U/ ml prot。FAC(10 μmol/ L)单独孵育 30 min NOS的活性为 (10 .5 9± 0 .5 9) U/ ml prot,但是 FAC预处理再加 IL - 2后 ,NOS活性显著降低为 (15 .71± 0 .89) U/ ml prot;高钙 (2 .5 mmol/ L )预处理 ,不改变 FAC对     

维生素K3通过钙依赖钾通道影响豚鼠结肠平滑肌收缩

目的 探讨维生素K3松弛胃肠道平滑肌的机制.方法 采用TD-112S型传感器测量豚鼠结肠平滑肌肌条收缩幅值、频率;用EPC10膜片钳放大器测量全细胞模式下细胞膜钙依赖钾电流[IK(ca)].结果 浓度为40、100、400、800 μmol/L的维生素K3作用后,肌条收缩频率分别为对照组的79%±4%,58%±5%,33%±4%,12%±3%(均P＜0.01).收缩强度分别为对照组的77%±10%,54%±7%,30%±6%,11%±4%(均P＜0.01).在+60 mV,I K(ca)值分别为对照组的120%±18%,149%±12%,197%±19%,223%±14%(均P＜0.01).结论 维生素K3能抑制平滑肌自发性收缩频率和强度,增强细胞膜IK(ca),且呈浓度依赖性.其机制与钙依赖钾通道的激活,促进钾离子外流有关.     

神经降压素在家兔压力感受性反射中的作用

采用电刺激减压神经及牵拉颈动脉窦的方法兴奋压力感受器,观察在产生减压效应时,血浆及某些脑区内神经降压素含量的改变,以探讨其在家兔压力感受性反射中的作用.结果表明,电刺激减压神经及牵拉颈动脉窦产生明显的减压效应时,家兔延髓、垂体、下丘脑及血浆内神经降压素含量明显增高.提示内源性神经降压素可能参与家兔压力感受性反射的调节过程.     

Effects of nitric oxide and hydrogen sulfide on the relaxation of pulmonary arteries in rats

Background The balance between vasodilation and vasoconstriction plays a major role in maintaining vascular homeostasis. However, the underlying mechanisms are unclear. More and more evidence suggested that there was an interaction in the regulation of vasorelaxation between nitric oxide （NO） and hydrogen sulfide （H2S）. We explored the interaction between and effects of NO and H2S on the relaxation of pulmonary arteries in rats. Methods Seven male Sprague-Dawley rats were anaesthetized with chloral hydrate and the pulmonary arteries of each rat separated for the study of vascular activities. The vasorelaxing activities of pulmonary artery rings in response to different doses of a NO donor, sodium nitroprusside （SNP）, or a H2S donor, sodium hydrogensulfide （NariS）, were measured in vitro. When pulmonary artery rings were treated with a cystathionine-y-lyase inhibitor, DL-propargylglycine, in the presence of SNP or a nitric oxide synthase inhibitor, Nω-nitro-L-arginine methyl ester, in the presence of NariS, the changes in relaxing activities were analyzed. Results The relaxation of pulmonary artery rings was in a dose dependent manner in response to either SNP or NariS. The relaxation rates of pulmonary artery rings increased from （30.90±4.62） % to （60.50±8.08） % when the concentration of SNP increased from 1 pmol/L to 3 pmol/L and from （26.13±4.12） % to （53.09±14.01） % when the concentration of NariS increased from 25 pmol/L to 100 μmol/L. However, when appropriate inhibitor was added, the relaxation responses to SNP and NariS decreased. Conclusions The results suggested that similarly to NO, H2S acted as a vasorelaxant either independently of, or synergistically with NO in the regulation of vasorelaxation. The interaction between NO and H2S played an important role in regulating relaxing activities of pulmonary arteries.     

Effect of temperature on the activation of myocardial KATP channel in guinea pig ventricular myocytes: a pilot study by whole cell patch clamp recording

Background The myocardial ATP sensitive potassium channel (K(ATP) channel) has been known for more than two decades, the properties of this channel have been intensively investigated, especially the myocardial protection effect by opening this channel. Numerous studies, including hypothermic, using K(ATP) agonists to achieve a hyperpolarizing cardioplegic arrest, have shown a better myocardial protection than potassium arrest. However, there is no evidence showing that K(ATP) channel could be opened by its agonists under profound hypothermia. We investigated the effect of temperature on activation of myocardial K(ATP) channel by nicorandil.Methods Isolated ventricular myocytes were obtained by collagenase digestion of the hearts of guinea pigs and stored in KB solution at 4&#730;C. With a steady ground current, the myocytes were perfused with 1 mmol/L nicorandil until a steady IK(ATP) occurred. Then the cells were perfused with 1 mmol/L nicorandil plus 1 &micro;mol/L glybenclamide. Currents signals were recorded on whole cells using patch clamp technique at several temperatures. The temperature of the bath solution around myocytes was monitored and was controlled at 4&#730;C, 10&#730;C, 20&#730;C, 25&#730;C and 35&#730;C respectively. About 10 cells were tested at each temperature, the cells were considered useful only when the outward current could be induced by nicorandil and blocked by glybenclamide. All data were analyzed using Graphpad PRISM 3.0 (Graphpad, San Diego, CA, USA). Nonlinear curve fitting was done in Clampfit (Axon) or Sigmaplot (SPSS). Results At 4&#730;C, 10&#730;C, 20&#730;C, 25&#730;C and 35&#730;C, the time needed to open the myocardial K(ATP) channel was (81.0±0) minutes, (50.5±11.7) minutes, (28.8±2.3) minutes, (9.4±10.2) minutes and (2.3±1.0) minutes respectively (P=0.003). The linear relationship between temperature and time needed to open the channel was y (min) = (4348.790－124.277x)/60, where y (min) is time needed to open K(ATP) channel, x is temperature, correlation coefficient r =－0.942 (P=0.00), regression coefficient b =－124.277 (P=0.00). The current densities among different temperatures were statistically different (P=0.022), the current density was greater after the activation of K(ATP) channel at higher temperatures. The lower the temperature, the fewer cells in which K(ATP) channels could be opened. At 4&#730;C, only one cell in which the K(ATP) channel could be opened, took a quite long time (81 minutes) and the I-V curve was quite untypical.Conclusions K(ATP) channel activated by nicorandil is temperature dependent and the temperature linearly related to time needed to open K(ATP) channel; the lower the temperature, the longer the time needed to open channel and the smaller the current density. At profound hypothermia, it is difficult to activate K(ATP) channels.     

中枢内源性乙酰胆碱对颈动脉窦压力感受器反射的影响

目的探讨中枢内源性乙酰胆碱（ACh）对颈动脉窦压力感受器反射（CSR）的作用。方法 SD大鼠麻醉后孤离其双侧颈动脉窦区,将不同窦内压（ISP）与其对应的平均动脉压（MAP）值进行Logistic曲线方程拟合,求得ISP-MAP关系曲线及其反射特征参数,观察侧脑室注射不同剂量的拟胆碱药毒扁豆碱（PHY）对CSR的影响。结果侧脑室分别注射低（1.8 mmol/L）、中（3.6 mmol/L）、高（5.4 mmol/L）剂量的PHY可导致ISP-MAP关系曲线在ISP 120～280 mmHg区间明显依次上移（P〈0.05）,ISP-增益关系曲线中部明显依次下移（P〈0.05）,反射参数中调定点、阈压、饱和压和最大增益时的窦内压值明显增大（P〈0.05）,MAP反射变动范围及反射最大增益明显减小（P〈0.05）。结论 PHY引起中枢内源性ACh增多,对CSR具有抑制性重调定作用,且这种效应呈现明显的剂量依赖性。     

静脉麻醉药对脂多糖诱导的神经胶质细胞产生TNF-α的影响

目的:神经胶质细胞介导的炎性反应与中枢神经系统多种病理过程有关,本研究旨在探讨静脉麻醉药对神经系统炎性损伤可能的保护作用.方法:本研究采用体外原代培养神经胶质细胞,以细菌脂多糖(LPS)诱导神经胶质细胞的炎性反应,实验分为8组:空白对照组(C组)、LPS对照组(L组)、100 μmol/L氯胺酮加LPS组(K1组)、1 000 μmol/L氯胺酮加LPS组(K2组)、30 μmol/L丙泊酚加LPS组(P1组)、300 μmol/L丙泊酚加LPS组(P2组)、3 μmol/L咪唑安定加LPS组(M1组)和30 μmol/L咪唑安定加LPS组(M2组),放射免疫法检测神经胶质细胞的炎性介质TNF-α的产生.结果:L组、K1组、K2组、P1组、P2组、M1组和M2组TNF-α较C组明显增高,差异有统计学意义(P＜0.05).K1组和K2组较L组TNF-α的生成减少,差异有统计学意义(P＜0.05),P1组、P2组、M1组和M2组与L组比较差异无统计学意义(P＞0.05).结论:氯胺酮可抑制神经胶质细胞的炎性反应中的TNF-α的释放,由此产生一定的抗炎作用.而丙泊酚和咪唑安定对LPS诱导的神经胶质细胞的TNF-α的产生无明显影响.