盐酸丙哌维林对膀胱平滑肌收缩的影响(英文)

观察了盐酸丙哌维林 ( Pro)对离体豚鼠膀胱平滑肌自动节律性收缩和 KCl诱导离体豚鼠膀胱平滑肌收缩的影响 ;同时观察了 Pro对家犬在体膀胱自动节律性收缩的影响 .Pro在 1 ,1 0 μmol· L-1浓度时 ,对离体豚鼠膀胱平滑肌自动节律性活动具有兴奋作用 ,可使自动节律性收缩频率增加 ,幅度加大 ;在 1 0 0μmol· L-1浓度时则表现为抑制作用 ,可完全抑制豚鼠膀胱平滑肌的自动节律性收缩 ,同时可使平滑肌松弛 ,基础张力降低 .Pro对 KCl引起的豚鼠离体膀胱平滑肌的收缩具有明显的抑制作用 ,在 1 ,1 0 ,1 0 0 μmol· L-1浓度时对 KCl诱导豚鼠离体膀胱平滑肌收缩的抑制率分别为 ( 7.4±6.5) % ,( 31 .3± 1 2 .8) % ,( 68.4± 7.1 ) % ,其 IC50 为( 2 5.2± 4.7) μmol·L-1.十二指肠给 Pro对在体家犬膀胱自动节律性收缩具有明显的抑制作用 ,60 ,30mg· kg-1可明显降低膀胱自动节律性收缩频率和幅度且具有剂量依赖性 ,与药前比有显著性差异 ,60 mg· kg-1药后 1 0 min即可起效 ,药效可持续 90min,Pro在上述剂量下对血压 ,心率无明显影响 .本实验结果提示 Pro在低剂量时对离体膀胱自动节律性收缩具有一定的兴奋作用 ,在高剂量时则表现为明显的抑制作用 ;Pro对 KCl诱导的豚鼠离体膀胱平滑肌收缩和膀胱扩张诱导的家?     

双白术内酯对豚鼠离体心房肌的作用

目的　以豚鼠离体心房肌为材料 ,研究新结构化合物双白术内酯对离体心房肌的作用。方法　采用豚鼠离体心房肌 ,测定给药前后心房的心率、心肌收缩力 ,左心房静息后增强作用及正性阶梯现象。结果　双白术内酯 (终浓度为1 19× 10 -5mol·L-1)能明显降低豚鼠离体右心房肌的收缩力 ,同时减慢其心率 ,此作用可完全被阿托品取消 ;双白术内酯使豚鼠离体左心房肌的正性阶梯作用降低 ,对左心房肌的静息后增强作用无影响。结论　双白术内酯对豚鼠离体心房肌有负性肌力和负性频率作用     

Urocortin对大鼠和兔离体心肌组织的选择性正性肌力效应

目的研究urocortin对心脏的作用。方法采用大鼠及兔离体右心房肌,左(大鼠),右(兔)心室乳头肌和大鼠离体右心室肌条标本,观察urocortin对心肌收缩力及心率的影响;采用细胞内微电极技术观察urocortin对大鼠离体乳头肌和左心房肌细胞动作电位的影响。结果Urocortin 1~30 nmol.L-1浓度依赖性地增强大鼠右心房心肌收缩力,urocortin10和30 nmol.L-1使收缩力分别增加(38±16)%和(61±17)%;urocortin的正性肌力作用明显强于同等浓度去甲肾上腺素的正性肌力作用。Urocortin不影响大鼠离体右心房的心率,左室乳头肌和右心室肌条的收缩力,对兔离体右心房和右室乳头肌亦无明显作用;β受体激动剂对上述标本则产生明显的正性频率作用和正性肌力作用。Urocortin 30~300nmol.L-1明显升高大鼠左心室乳头肌的动作电位幅值和超射值;urocortin 30~100 nmol.L-1明显升高大鼠左心房肌的动作电位幅值和超射值。结论Uro-cortin对大鼠离体心房具有很强的正性肌力作用。Urocortin的正性肌力作用具有明显的种属差异和组织学差异。     

盐酸小檗碱对毒蕈碱性受体的激动作用

用大鼠离体胸主动脉环和豚鼠离体气管条功能实验及放射配基受体结合实验研究盐酸小檗碱（Ber）对组织毒蕈碱受体（Ｍ受体）的作用. 结果表明较高浓度的Ber（≥20 μmol·L^-1）对有内皮的动脉环具直接舒张作用;在去内皮或阻断Ｍ受体后,其舒张作用被完全抑制. Ber使豚鼠离体气管条产生浓度依赖性收缩,此作用可被阿托品拮抗,其pA2值为9.8. 放射配基受体结合实验显示,Ber对大鼠的唾液腺, 大脑皮质和心脏Ｍ受体均有中度亲和力,且使［³H］-二苯羟乙酸奎宁酯（QNB）与3种组织Ｍ受体结合的Ｋ_d值增大,最大结合量不变. 其Ｋ_i值分别为(7.6±1.3), (1.6±0.9)和(0.58±0.07) μmol·L^-1. 结果提示,Ber有Ｍ受体激动作用.     

国产扑喘息敏(Procaterol)的药理研究

扑喘息敏5×10~(-5)-2×10~(-3)mg/ml 对豚鼠离体气管有直接弛张作用,4×10~(-4)-4×10~(-3)mg/ml 可对抗组织胺收缩离体气管的作用,5mg/kg ip 可延长组织胺对豚鼠所致呼吸困难的潜伏期,20mg/kg iv 对麻醉兔有明显而暂时的降血压作用,2.5×10~(-3)mg/ml 可使豚鼠离体心脏收缩幅度增大,心率增加,1×10~(-2)mg/ml 可使灌流液流量和心率增加,3.6×10~(-2)mg/ml、9×10~(-2)mg/ml 可使部分豚鼠离体回肠收缩幅度增大,频率增加,张力增加。扑喘息敏给小白鼠ip,LD_(50)为390.5±20.3mg/kg。     

去甲乌药碱对实验性心力衰竭的治疗作用

去甲乌药碱(DMC)是中药附子的有效成分之一。静脉滴注DMC2μg/kg/min共5min,使豚鼠正常心脏的收缩力明显加强,LVSP和LV dP/dt_max分别增加58±7和25±7%;心衰后,LVSP和LV dP/dt_max分别下降到心衰前的40±5和30.5±2.8%。DMC可使之恢复到79±14和75±9.9%,DMC也能加强离体豚鼠衰竭心脏的收缩力。DMC的强心作用与ISO相似,但前者作用较弱,作用维持时间较长,这可能与他们的作用机制不同有关。     

小檗碱对心肌细胞I_(K1)、I_K及HERG通道的抑制作用(英文)

目的:研究小檗碱(Ber)对豚鼠心室肌细胞钾通道和动作电位作用,以及在蛙卵中表达的人的HERG通道的作用。方法:酶解方法分离单个心肌细胞,采用全细胞膜片箝方法记录钾离子电流及动作电位,基因箝技术研究HERG通道电流。结果:Ber可显著延长动作电位时程,并呈剂量依赖性。Ber 100μmol/L使APD_(90)由对照的(450±48)ms延长至(888±90)ms(n=6,P<0.01)。Ber对I_(Kl)及I_K呈剂量依赖性抑制作用。Ber 100μmol/L对I_(Kl)的抑制率达65％±7％(n=6,P<0.01)。Ber 50μmol/L对I_K的抑制率达57％±6％;对I_(Ktail)的抑制率达53％±6％。Ber对I_K作用呈现电压依赖性。Ber对在蛙卵中表达的HERG通道具有很强的阻断作用,IC_(50)为75μmol/L,此阻断作用也呈电压依赖性。结论:Ber可使动作电位时程明显延长,对I_(Kl)及I_K具有阻断作用。Ber可显著抑制HERG通道。Ber抗心律失常的机制与其抑制I_(Kl)、I_K及HERG通道密切相关。     

小檗碱对大鼠心输出量及哇巴因作用的影响(英文)

在麻醉大鼠,小檗碱(Ber)20mg/kgiv可明显提高心指数和心搏出量指数。在离体豚鼠左心房,Ber 0.1μmol/L使哇巴因正性肌力作用量效曲线左移,最大反应增大。Ber 10,30μmol/L可增大哇巴因的最大正性肌力作用;使达峰作用所需哇巴因的浓度减少。Ber 30,100μmol/L使哇巴因引起中毒的浓度增大。缺氧对Ber的正性肌力作用影响不大。上述结果提示Ber可增加心输出量,增大哇巴因治疗的安全宽度。     

氧化苦参碱的强心作用

用多种实验动物研究了氧化苦参碱的强心作用,结果表明:氧化苦参碱(05、5、50mol/L)能明显增加正常离体蟾蜍心肌收缩力、心输出量,强心同时不增加心率;显著增加戊巴比妥钠和低钙离体心衰模型的心肌收缩力、心输出量(P<005或P<001);50mmol/L可使心肌收缩力、心输出量完全恢复到心衰前水平,对心率无明显影响;能不同程度地加强离体豚鼠、大鼠、兔乳头肌的收缩力,均呈现良好的量效关系,对豚鼠乳头肌更为敏感;增加大鼠离体右心房心肌收缩力同时降低其自发收缩频率(P<001).     

绞股蓝总皂甙对离体豚鼠心房生理特性的影响

绞股蓝总皂甙能明显延长离休豚鼠心房功能性不应期（ＦＲＰ）．其值由给药前的２０１±１２ｍｓ延长至给药后的２２５±９ｍｓ。绞股蓝总皂甙还能浓度依赖性地降低离体豚鼠右心房的自律性．绞股蓝总皂甙对离体豚鼠心房肌的收缩性无明显影响．     

小檗碱的负性变时作用

小檗碱(Ber)4mg/kg ⅳ使正常大鼠的血压(BP)降低,心率(HR)不变;迷走神经切断大鼠的BP降低,HR减慢;毁脊髓大鼠的HR减慢,BP不变。在离体豚鼠右心房,Ber产生负性变时作用,且不被阿托品对抗。Ber使异丙肾上腺素、组胺和CaCl_2正性变时作用的量效曲线非平行性右移,最大反应压低,呈非竞争性拮抗作用,其pD_2分别为4.82,4.51和4.68。结果表明Ber对正常大鼠的负性变时作用,可因其降压所致的反射性HR加快而抵消。Ber的负性变时作用可能与心肌M,β和H_2受体无关,也不是选择性阻滞Ca~(2+)内流所致。     

Effect of ethacrynic acid on spontaneous contractions of isolated guinea-pig atria

The effect of different doses of ethacrynic acid (EA), 25–200 μg/ml, has been studied on the rate and force of contractions of isolated guinea-pig atria. It has been shown that EA produces dose-dependent increases in force of contraction (31–72%) and of rate (13–36%).Pretreatment of guinea pigs with reserpine, 5 mg/kg or of the isolated atria with propranolol (2 μg/ml) inhibited the inotropic and chronotropic effects of EA. Pretreatment of the atria with cocaine (5 μg/ml) inhibited the inotropic effect of EA, but had no significant effect on its chronotropic action.It is concluded that in guinea-pig atria, the positive inotropic and chronotropic action of EA, is probably due to the release of endogenous catecholamines.     

Possible Involvement of Protein Kinase C in the Modulation of Inotropic and Chronotropic Effects Induced by Ouabain in Rat Right Atrial Muscles

Modulations of the inotropic and chronotropic effects of ouabain and protein kinase C (PKC) stimulation with phorbol esters in rat right atria were examined. Cumulative administration of ouabain (3–30 μm ) caused a positive inotropic effect in a concentration-dependent manner, but did not produce a chronotropic effect. A single administration of ouabain (30 μm ) also had similar effects: +744 ± 84% (n = 23, P < 0.01) in the contractile force and ?0.7 ± 1.3% (n = 23, P > 0.05) in the sinus rate. Addition of phorbol esters reinforced the ouabain-evoked positive inotropic effect: 26.5 ± 8.9% (n = 6, P < 0.05) with 100 μm 4-β-phorbol-12,13-dibutyrate (PDB), and 6.4 ± 3.3% (n = 6, P > 0.05) with 100 μm 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Simultaneously, the mixture of ouabain and phorbol ester raised the resting tension. Phorbol esters alone caused a positive inotropic effect (by about 21–27%). Non-PKC activating phorbol ester, 4-α-phorbol-12,13-didecanoate (PDD, 100 μm ), did not have any effect. Pretreatment with the PKC inhibitor (staurosporine 100 μm ) significantly decreased the ouabain-induced positive inotropic effect and caused a negative chronotropic effect, but H-7 (1-(5-isoquinolinylsulphonyl)-2-methylpiperazine dihydrochloride) (5 μm ) had no effect. These results suggest that PKC stimulation may be involved in the ouabain-evoked responses in the right atria of rat as seen by increased cellular Ca²⁺ concentration (and Ca²⁺-sensitivity); thus the positive inotropic effect may not be due only to modulation of Na⁺/K⁺ pump activity.     

吡喹酮及其对映异构体对离体大鼠心房肌生理特性的影响

吡喹酮(praziquantel,PQT)对心肌生理特性的影响有立体选择性。(-)-PQT对离体大鼠左心房的正性肌力作用的效能和强度均比(+)-PQT和(±)-PQT小。用维拉帕米可明显减弱PQT及其对映异构体的正性肌力作用。在浓度为100μmol/1时,PQT及其对映异构体对离体大鼠右心房均有负性频率作用,而当30μmol/1时仅(+)-PQT对频率有明显影响。它们尚可诱发右心房心律失常,其发生率以(+)-PQT最高,(-)-PQT最低,(±)-PQT居中。(+)-和(±)-PQT可明显缩短左房不应期。(+)-PQT还可明显降低左房自律性,而(-)-PQT对不应期,自律性均无影响。     

Effects of capsaicin desensitization on the stimulatory effect of kinins, prostaglandins, biogenic amines and various drugs in guinea-pig isolated atria.

1. A simple desensitization protocol was set up using capsaicin and isolated, spontaneously beating atria of guinea-pigs to assess the possible participation of cardiac, capsaicin-sensitive, substance P (SP)- and calcitonin gene-related peptide (CGRP)-containing sensory nerve fibres, in the cardiac stimulatory effects of bradykinin (Bk), kallidin (Kd), 5-hydroxytryptamine (5-HT), histamine, prostaglandin E2 (PGE2), prostaglandin E1 (PGE1), prostaglandin F2 alpha, (PGF2 alpha), adrenaline (Ad), glucagon, nicotine and angiotensin II (AII). 2. The positive chronotropic and inotropic effects of Bk, Kd and 5-HT were markedly reduced in capsaicin-desensitized atria compared to control. The percentage inhibition of the chronotropic and inotropic responses to the three agonists seemed to be inversely related to the concentration of agonist used and to vary also with the type of cardiac effect produced by the drug (for Bk the percentage inhibition was: 36-81% (chronotropic effect) and 62-86% (inotropic effect); for Kd: 61-78% (chronotropic effect) and 53-77% (inotropic effect); for 5-HT: 25-66% (chronotropic effect) and 40-64% (inotropic effect]. 3. The positive chronotropic and inotropic effects of histamine, PGE1, PGE2, PGF2 alpha, glucagon and AII had similar amplitudes in capsaicin-desensitized and control atria. 4. The positive chronotropic and inotropic effects of Ad and nicotine were differentially affected by capsaicin desensitization. The inotropic effects of 7.5 x 10(-7) and 7.5 x 10(-6) M Ad were reduced by 41 and 27% respectively, in capsaicin-desensitized atria compared to control. The chronotropic effects of 1.54 x 10(-5) and 6.17 x 10(-5) M nicotine were inhibited by 57 and 26% respectively, by capsaicin desensitization. On the other hand, the chronotropic effect of Ad and the inotropic action of nicotine were of similar amplitude in capsaicin-desensitized and control atria. 5. These results were taken as an indication that a substantial part of the chronotropic and inotropic effects of Bk, Kd or 5-HT in guinea-pig atria, unlike those of histamine, PGE1, PGE2 PGF2 alpha, glucagon and AII, might be the result of stimulation of capsaicin-sensitive, SP- and CGRP- containing sensory nerve fibres. The slight, differential inhibition of the chronotropic and inotropic effects of Ad and nicotine by capsaicin desensitization suggests a minor contribution by cardiac, capsaicin-sensitive sensory nerve fibres to the effects of nicotine and Ad in guinea-pig atria.     

Evidence for a prostacyclin-mediated chronotropic effect of angiotensin II in the isolated cat right atria

The positive chronotropic effect of angiotensin II was studied on the isolated spontaneously beating cat right atria. Angiotensin II and prostacyclin produced similar positive chronotropic and inotropic effects which were not affected by beta-adrenoceptor and histamine H2-receptor blockers. [Sar1,Ile8] angiotensin II, however, inhibited the positive chronotropic and inotropic responses to angiotensin II without altering that to prostacyclin, noradrenaline and histamine. Nicotine completely abolished the positive chronotropic action of angiontensin II without altering its positive inotropic effect. Nicotine failed to abolish the effects of prostacyclin, noradrenaline and histamine on the rate and contractility. These results were taken as evidence that the angiotensin II-induced increase in heart rate is probably mediated through the increase of prostacyclin biosynthesis in the isolated cat right atria.     

Marine toxins from the Pacific—IX Some effects of ciguatoxin on isolated mammalian atria

Ciguatoxin produced an initial negative inotropic and chronotropic effect which was followed by a positive inotropic and chronotropic effect on the isolated rat atria. The initial depression could be effectively blocked by atropine (1 × 10⁻⁷ g per ml), and partially blocked by hexamethonium or hemicholinium-3 (2 × 10⁻⁵ g per ml). The positive inotropic and chronotropic action of ciguatoxin was reduced by pretreating the atria with MJ-1999 (1 × 10⁻⁶ g per ml) or guanethidine (1 × 10⁻⁶ g per ml). Abolition of the response to ciguatoxin could also be accomplished with a single dose of 2 mg per kg of reserpine given to the rat 24 hr before isolating the heart. It is not yet possible to correlate inotropic and chronotropic effects of the toxin with the release of catecholamines, but it seems likely that excitatory effect of the toxin may be elicited by a release of catecholamines from their stores.     

Effect of diamide on isolated guinea pig atria

Diamide [(diazinedicarboxylic acid-bis (dimethylamide)] 50 micrograms/ml induced a positive inotropic and chronotropic effect on spontaneously beating atria from normal and reserpine pretreated guinea pigs and a positive inotropic action on electrically driven left atria. Cumulative addition of diamide 600 micrograms/ml caused a systolic standstill of atria. D(-) INPEA 2 micrograms/ml, a beta-adrenergic blocking agent, antagonized the positive chronotropic action of diamide 50 micrograms/ml while it did not affect the positive inotropic action caused by diamide. In isolated atria perfused with Ca2+ free medium and recovered by stepwise addition of calcium chloride, the calcium level required to restore normal activity was 1.04 mmol/1 while it was 0.52 mmol/l in the presence of diamide. Ruthenium red 10 micrograms/ml, a specific inhibitor of calcium transport in mitochondria, antagonized diamide-induced recovery of the cardiac activity in calcium poor medium. Two different mechanisms, that involve calcium movements and beta-receptor, have been proposed for diamide action on heart muscle.     

A COMPARISON OF THE CARDIAC ACTIONS OF DOPAMINE AND NORADRENALINE IN ANAESTHETIZED DOGS AND GUINEA-PIG ATRIA

1. The positive chronotropic and inotropic actions of dopamine and noradrena-line have been compared in anaesthetized dogs and isolated guinea-pig atria. 2. Inotropic activity was measured with a strain-gauge arch in vagotomized dogs or estimated from max (dp/dt) in dogs with denervated hearts. 3. The effects of propranolol and haloperidol on the concentration-response curves to both amines were studied in isolated atria. 4. In anaesthetized vagotomized dogs noradrenaline was more potent than dopamine but dopamine appeared to have a selective inotropic action, less apparent with noradrenaline. In denervated hearts, doses of noradrenaline and dopamine which caused similar increases in max (dp/dt) also caused similar increases in heart rate. 5. In isolated atrial preparations, concentrations of dopamine and noradrenaline which produced similar increases in force of contraction also had similar chronotropic effects. 6. Propranolol produced a shift to the right of the concentration-response curves to both dopamine and noradrenaline but the antagonism of noradrenaline was quantitatively greater. Haloperidol had no effect in concentrations below those found to cause general tissue depression. 7. It is concluded that neither dopamine nor noradrenaline show any real difference in their relative inotropic and chronotropic activities in the absence of autonomic innervation.     

Functional studies in atrium overexpressing A1-adenosine receptors

1. Adenosine and the A1-adenosine receptor agonist R-PIA, exerted a negative inotropic effect in isolated, electrically driven left atria of wild-type mice. 2. In left atria of mice overexpressing the A1-adenosine receptor, adenosine and R-PIA exerted a positive inotropic effect. 3. The positive inotropic effect of adenosine and R-PIA in transgenic atria could be blocked by the A1-adenosine receptor antagonist DPCPX. 4. In the presence of isoprenaline, adenosine exerted a negative inotropic effect in wild-type atria but a positive inotropic effect in atria from A1-adenosine receptor overexpressing mice. 5. The rate of beating in right atria was lower in mice overexpressing A1-adenosine receptors compared with wild-type. 6. Adenosine exerted comparable negative chronotropic effects in right atria from both A1-adenosine receptor overexpressing and wild-type mice. 7. A1-adenosine receptor overexpression in the mouse heart can reverse the inotropic but not the chronotropic effects of adenosine, implying different receptor-effector coupling mechanisms.