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<p><b>OBJECTIVE</b>To evaluate the effects of Rbl on action potentials and force of contraction in guinea pig ventricular papillary muscles.</p><p><b>METHOD</b>The ventricular papillary muscles of guinea pig were isolated regularly and immersed with Tyrode, s solution. The effects of Rbl (purified saponins of panaxnotoginseng) on the action potentials (AP), the slow action potentials and the force of contraction (FC) of the muscles were studied. The AP and FC were measured synchronously.</p><p><b>RESULT</b>Rbl shortened the duration of AP, including APD2O and APD90, and reduced the FC(n = 5, P < 0.01), but didn't affect the rest potential (RP), the amplitude of action potential (APA), overshot (OS) and maximal upstrok velocity (Vmax). Rbl also decreased the APA of slow action potential, but quinidine had no such effects.</p><p><b>CONCLUSION</b>Rbl may be a channel blocker.</p>
Subject(s)
Animals , Female , Male , Action Potentials , Calcium Channel Blockers , Pharmacology , Drugs, Chinese Herbal , Pharmacology , Ginsenosides , Pharmacology , Guinea Pigs , Myocardial Contraction , Panax , Chemistry , Papillary Muscles , PhysiologyABSTRACT
Ten mongrel dogs,divided randomly into a control group (A) and a cerebroplegia group (B) ,were supported by closed-chest cardiopulmonary bypass,subjected to 2 hours of hypothermic circulatory arrest at 18 C. In group B, oxygenated asanguineous solution 50ml/kg was infused into the carotid artery at the onset of arrest. and 10 ml/kg was supplemented every 30 minutes during 2hours arrest. Nothing was infused in group A. Then all animals were rewarmed to 37 C and killed 6 hours later At five time points cerebral cortex was collected to study adnosine triphosphate (ATP),malondialde hyde (MDA) and ultrastructure. Electroencephalography (EEG) was recorded continuously. In group A, ATP content decreased gradually from the beginning of arrest to the end of the experiment (P
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Objective To determine the role of adenosine A1 receptor system in the delayed protective effects of ischemic preconditioning(IPC) in brain ischemia.Methods Thirty-five rabbits weighing 2-2.5kg were randomly divided into 7 groups: control (group Ⅰ), 3-min ischemia (group Ⅱ), 10-min ischemia (group Ⅲ), IPC (group Ⅳ), N6-cyclopentyladenosine (CPA)(group V), 8-cyclopentyl-1,3-dipropylxanthine (DPCPX)+ IPC(group Ⅵ), and DPCPX+3-min ischemia (group Ⅶ).Cerebral ischemia was produced by occlusion of both carotid arteries in combination withdrawing blood to maintain MAP at 35-40 mmHg.After 3-min IPC and 3 days of recovery , cerebral ischemia was induced and lasted 10 min (model of delayed protective effects of IPC). Adenosine A1 receptor agonist CPA or antagonist DPCPX was used instead of IPC to evaluate the role of adenosine A1 receptor in the delayed protective effects of IPC.The expression of heat shock protein 70 (HSP70) was analyzed by immunohistochemistry.Neurons density and expression of HSP70 in the hippocampal CA1 region were examined and measured 3 days later.Results (1) CPA could reduce cerebral ischemic injury, but the effects of CPA were not as good as those of IPC (about 70% of IPC).After adenosine A1 receptors being blocked by DPCPX the delayed protective effects of IPC disappeared.(2) 3-min ischemia alone did not cause neuronal injury but induced obvious expression of HSP70.DPCPX not only could make 3-min ischemia cause injury but also reduce the expression of HSP70.Conclusions (1) The delayed protective effects of IPC is related with activation of adenosine A1 receptor system.(2) One of the mechanisms of the blocking effects of DPCPX may be due to the reduction in expression of HSP70 .
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Objective: To study the effect of low-dose dopamine on splanchnic DO_2/VO_2.in rabbit SMAO shock Method:Twenty rabbits were randomly devided into two groups:group A with dopamine,group B as control group. In group A dopamlne was infused at a rate of 5?g?kg~(-1)?min~(-1). SMAO shock model was induced in both groups. Cardiac output index(Cl),portal venous blood flow index (QpvI),mean arterial pressure (MAP),arterial. artiaI and portal venous blood gas analysis.arterial and portal venous serum lactate concentrations(ALT,PLT), total oxygen delivery/oxygen consumption (TDO_2/TVO_2), splanchnic oxygen delivery/oxygen consumption (SDO_2/SVO_2). oxygen extraction ratio(O_2ER) were measured respectively. Result: QpvI, SDO_2,SVO_2 were higher in group A than those of group B (P0.05). CI,MAP, TDO_2/TVO_2 decreased. TO_2ER and SO_2ER increased in both of groups during shock, but without significant differences between both groups. Conclusion: Low-dose dopamine has beneficial effects by increasing portal venous blood perfusion and improving splanchnic oxygenation during SMAO shock in rabbits. but no effects on systemic oxygenation of shock.
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A certain amount of potassium chloride is required to correct the hypokalemia occuring commonly during perioperation,but the overdosage may be harmful. To investigate the proper dose of KCl,40 adult rabbits were randomly and evenly assigned to be intravenously infused with normal saline(group Ⅰ),or saline containing 4,25 or 50 mmol/L KCI (group Ⅱ,Ⅲ,Ⅳ),at rate of 10 ml?kg~(-1)?h~(-1) during operation respectively. As compared with those before operation,the serum level of potassium decreased significantly in group Ⅰ and Ⅱ, changed unsignificantly in group Ⅲ,and increased in group Ⅳ during and after operation;the potassium amounts in liver and skeletal muscles increased markedly after operation. S-T segment was depressed in group Ⅰ and Ⅱ,T wave became peaked in group Ⅳ, and ECG remained normal in group Ⅲ. it is indicated that intravenous KCl infusion at concentration 25 mmol/L and rate of 10ml?kg~(-1)?h~(-1) may properly correct the hypokalemia during perioperation,and the occurance of perioperatine hypokelemia may be related to the uptake of liver and skeletal muscles
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The purpose of this paper was to find a safe and effective concentration of lido- caine in intravenous combining anesthesia.33 cases had been maintained with the intravenous instillation of 0.5% lidocaine and 0.1% scotine the lidocaine concentrations at the period of after introduction,30＇,60＇,90＇,120＇and recovery were measured respectively.The safty and effective range of this drug would be 2.1—5?g/ml. Also,in this paper,the relationship between the rate of instilation and the concentration of Lidocaine was studied.There was a positive correlation between the drope per minute amd the concentration during the period of the first 60 minutes. After 90 minutes from the beginning,there was no linear correlation.If we want to maintain the safty and effective blood concentration(2.1—5?g/ml), the necessary rate of instillation is 46?10 drops/minute during the first 60 minutes and 27.8?5 drops/minute after 90 minutes.This result shows that lidocaine is easy to accumulate obviously in the body.If we want the patient to recover at the time of the operation just performed,we must stop this drug 50 miuutes before the operation is finished.