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AIM To study the effects of A 3 site (components), extracted from Angelica naphtha (total oil),on physiological properties of isolated rat atrium and action potential of isolated guinea pig ventricular papillary muscles. METHODS Spontaneous beats, contractile force and functional refractory period(FRP) of isolated atrial muscle were recorded according to the regular methods. Standard microelectrode intracellular recording technique was used to record action potential(AP) of ventricular papillary muscles. RESULTS A 3 site(10～160 mg?L -1 ) dramatically inhibited spontaneous beats of isolated rat right atrium and made beats stop with 160 mg?L -1 . A 3 site concentration dependently reduced contractile force of isolated rat left atrium induced by electrostimulating, with the IC 50 value of 52 3 mg?L -1 . A 3 site(40～100 mg?L -1 ) obviously prolonged FRP. The FRP was prolonged from 106 ms (as control) to 130 ms at final concentration of 100 mg?L -1 . A 3 site decreased action potential amplitude (APA), shortened 20%APD(APD 20 ) and 90%APD(APD 90 ), but had no significant effect on RP of AP. CONCLUSION The mechanism of these effects of A 3 site on myocardial physiological properties and action potential was probably associated with blocking the influx of Ca 2+ and Na +, promoting K + outflux.
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AIM: To study the effects of xanthotoxol (XT) on physiological characteristics and its mechanism in isolated guinea pig atria. METHODS: It was determined by the contractile amplitude,excitability and the spontaneous beats in the right atria,respectively. RESULTS: In the experiment of contractile amplitude,after 15 min of administration of XT 20, 40 and 80 ?mol?L -1 ,the contractile force of left atria was 0.85 , 0.68 ,and 0.48 g,respectively (P
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AIM: To study the mechanism of effects about total flavones of choeropondias axillaris (TFC) to heart. METHODS: The effects of TFC on contractility were investigated through acting on the guinea pig right ventricle papillary muscles. RESULTS: TFC decreased both the contractility and contraction rate of papillary muscles. The quantity-effect curve of CaCl2 was shifted to right after giving TFC. TFC 30.4 μmol·L-1 prolonged remarkably the functional refractory period (FRP) of guinea pig right ventricle papillary muscles, but exerted no effect on excitability. CONCLUSION: TFC can inhibit the Ca2+ influx into cell in a concentration-dependent manner.
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Dauricine ( Dau ) significantly prolonged monophasic action potential duration of 50% and 90% repolarization ( MAPD50 and MAPD90 ) and functional refractory period (FRP)of the hearts in anesthetized cats in dose-dependent manner. At 9 mg/kg of Dau, MAPD50 was increased from 170?19 ms to 197?20 ms; MAPD90 from 216?16 ms to 249?18 ms; FRP from 177 ? 15 ms to 238 ? 20 ms.Dau 5 mg/kg iv followed by constant perfusion for 30 min could prevent the shortening of MAPD50 in the ischemic boundary area ( BA ) and increased FRP in the non-ischemic area ( NA ) , ischemic central area ( CA ) and BA, and markedly reduced the extent of dispersion of FRP of hearts in anesthetized cats. The results suggest that the antagonizing effect of Dau on the arrhythmias caused by acute myocardial ischemia and reperfusion might be related to its action of prolonging FRP and decreasing the dispersion of FRP in ischemic hearts.
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The effect of 4 -Phosphate- lydroxypiperaquine ( PHPQ) on the phsiologic properties in isolated auricle of guinea pig was studied.Twenty minutes after PHPQ 30 ?mol/L was added, the contractility & dT/dtmax of the left atria of guinea pig were decreased to 74.4 ? ( SD ) 5.3%(n=6, P
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Corydalis amabilis Migo total alkaloids (COAMTA) possessed antihypertensive and vaso-dilatative action in animal experiments. Its effects on the physiological properties in isolated guinea pig papillary muscles & atrium preparations were described in this papar.10mg/L COAMTA markedly prolonged the functional refractory period(FRP) and inhibited epinephrine induced automaticity. Suppression of normal & abnormal automaticity and prolongation of FRP may contribute to the effectiveness of COAMTA on arrhythmia.
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The effects of dl-Tetrahydropalmatine ( THP ) on the physiologic properties in the auricle of guinea pig and on isoproterenol and calcium-mediated positive chronotropic action in guinea pig atria were studied.30 minutes after THP 52 nM was added, the contractility was decreased to 53+ ( SD ) 17%(P0.05) in the left auricle of guinea pig. Furthermore, the contractility and automaticity of the right auricle were decreased to 48+13% (P
ABSTRACT
AIM To study the mechanism of effects about total flavones of choeropondias axillaris(TFC) to heart. METHODS The effects of TFC on contractility were investigated through acting on the guinea pig right ventricle papillary muscles. RESULTS ① TFC decreased both the contractility and contraction rate of papillary muscles. ②The quantity effect curve of CaCl 2 was shifted to right after giving TFC. ③TFC 30.4 ?mol?L -1 prolonged remarkably the functional refractory period (FRP) of guinea pig right ventricle papillary muscles, but exerted no effect on excitability. CONCLUSION TFC can inhibit the Ca 2+ influx into cell in a concentration dependent manner.
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Total cardiac glycosides isolated from dry fruit of Erysium chei- ranthoides L ( ETCG ) possesed positive inotropic effect. Its effects on the physiological properties of guinea pig left atria were studied. in this paper. The effects of ETCG on dose-response curve were investigated. The results showed that ETCG increased contractility of left atria significantly and dose-dependently .The pD2 value was 7.94. ETCG ( 0.17mg/L)increased significantly excitability and automaticity induced by epinephrine. ETCG(0.01mg/L ,0 .043mg/L ,0 .17mg/L)prolonged functional refractory period obviously.
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The effects of Na_2MoO_4 on experimental ventricular arrhythmias and isolated guinea pig atria are reported. Iv Na_2MoO_4, 8 mg/kg was found to increase the tolerant dose of ouabain to produce ventricular permature beats, ventricular tachycardia and ventricular fibrillation in guinea pigs. Na_2MoO_4 significantly counteracted the ventricular arrhythmias induced by BaCl_2 and aconitine in rats. Na_2MoO_4 10 ?g/10 g ip decreased the incidence of ventricular fibrillation by chloroform in mice, Na_2MoO_4 10 mg/kg did not produce antagonistic effect on the arrhythmias induced by chloroform-adrenaline in rabbits. Na_2MoO_4 0.1 mmol/L inhibited contractility of isolated guinea pig atria, prolonged the functional refractory period and makedly inhibited the frequency-dependent positive staircase phenomenon and the post-rest potentiation.
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Osthole, the coumarin isolated from the fruits of Cnidum monnieri (L.) Cusson. The effects of osthole on the physiological properties in isolated auricle of guinea pig were studied. It possesses dose—dependent negative inotropic effects, the BaCl_2 inducing automaticity was inhibited, and the functional refractory period (FRP) was prolonged, and the frequence of sinoatrial node was slowed The negative inotropism and automatism suggest that sothole mey be antagonis tic to Ca~(2+), while the decrease of excitability and the prolongation of FRP indicate that it may be due to its inhibition on Na~+ current. The decrease of automaticity and excitability and prolongation of FRP are thought to be its antiarrhythmic action.