Protective effect of antioxidant ionol in total ischemia of the heart

The effect of antioxidant ionol in total myocardial ischemia during 30 and 60 min, t = 20 degrees C and 37 degrees C was studied in 60 Wistar rats. The models of isolated perfused myocardium by Langendorf, Neely and that of heterotopic transplantation of myocardium to the rat peritoneal vessels were used. It has been shown that pretreatment of ionol (240 mg/kg before 24 h of ischemia) was accompanied by improvement of myocardial contractile and diastolic functions.     

Prevention of adrenaline-induced heart damage using the antioxidant ionol

Experiments on an isolated papillary muscle of the rat heart left ventricle have demonstrated that pretreatment with the antioxidant ionol prevents the disturbances of myocardial contractility caused by administration of a large dose of adrenaline. The data obtained are in agreement with the concept that the prophylactic action of antioxidants during stress is determined by the fact that they prevent activation of lipid peroxidation in the heart under the action of excess catecholamines.     

Limitation of ischemic necrosis by the use of antioxidant ionol

Inhibitory effect of Ionol on lipid peroxidation (LPO) in the infarction zone and out of it after experimental myocardial infarction in the experiments on rats was investigated. The results of measurements, performed by two independent methods: point counting and the computer image analysis were compared. It was shown that LPO activation out of the ischaemic zone was prevented and dimensions of the ischaemic necrosis were limited by Ionol, which did not influence LPO activation in the ischaemic zone. Data obtained by both methods coincide qualitatively, the computer image analysis being more sensitive and effective.     

腺苷抗豚鼠室性心律失常的电生理研究

实验用全细胞膜片钳技术在单个豚鼠心室肌细胞上研究了腺苷 (Ado)对正常及异丙肾上腺素 (Iso)致豚鼠心室肌细胞动作电位、迟后除极 (DAD)、L 型钙电流 (ICa.L)和短暂内向电流 (Iti)的作用。结果表明 :(1)Ado在2 0～ 10 0 μmol/L时对豚鼠心室肌细胞动作电位和ICa .L无明显直接作用 ,但却可明显降低Iso所致的动作电位时程(APD)延长和ICa .L峰值增大 ,Iso (10nmol/L)使细胞APD50 从 3 40± 2 1ms延长到 486± 2 8ms (P <0 0 1) ,APD90从 3 61± 17ms延长至 5 0 1± 2 9ms (P <0 0 1) ;ICa .L峰值从 - 6 5 3± 1 4pA/pF增大到 - 18 2 8± 2 4pA/pF (P <0 0 1) ,电流电压曲线明显左移和下移 ;Ado (5 0 μmol/L)使APD50 和APD90 降至 40 3± 19ms和 419± 2 6ms ,但并不影响动作电位其它参数 ,使ICa.L峰值降低至 - 10 2± 1 5pA/pF (P <0 0 1)。 (2 )Iso (3 0nmol/L)可诱发心室肌细胞产生DADs,其发生率为 10 0 % ;Ado (5 0 μmol/L)可完全抑制Iso引发DADs;细胞经 - 40～ +2 0mV、时程 2s的除极电压 ,Iso (3 0nmol/L)诱导出Iti,其发生率为 10 0 % ;Ado (5 0 μmol/L)可明显抑制Iso致Iti的发生 ,其发生率降为 14 3 %。研究结果提示 ,Ado对豚鼠心室肌细胞动作电位和ICa.L无明显直接作用 ,但却可显著降低Is     

Correction of lipid peroxidation disorders in experimental traumatic shock using the antioxidant ionol

The level of certain parameters of lipid peroxidation and the activity of lysosome hydrolases were studied on the shock model in rats. It was established that the traumatic shock in the experiment is accompanied by the growth of the level of over-oxidation products (malonic dialdehyde, diene conjugates), the rate of erythrocyte hemolysis as well as by an increase in the hydrolase activity. Administration of ionol (60 mg/kg) inhibits the higher activity of radical-free lipid oxidation, decreases the damage of membrane structure and the metabolism disturbance.     

An electrophysiological study of the sequential water swallowing

BackgroundSequential water swallowing (SWS) was mostly investigated by the videofluoroscopic and endoscopic methods. However some physiological features of SWS was rarely evaluated by neurophysiological techniques. Our aim was to investigate some neural and muscular changes on sequences of SWS using electromyography (EMG) methods.MethodsFifty-eight normal adults were investigated. SWS was initiated voluntarily with 50 ml and 100 ml water volumes from a cup. Submental EMG, respiratory signals, heart rate, and sympathetic skin responses (SSR) were measured during SWS.Key resultsAll parameters were increased significantly during the 100 ml SWS. During swallowing apnea period, compensatory respiration cycles occurred in 24% and 48% of participants in the 50 ml and 100 ml SWS, respectively. Heart rate increased during swallowing apnea. SSR were evoked just before and just after the SWS in more than halves of participants. A foreburst EMG in SM muscles at the initiation of SWS was recorded in 86% of normal participants. Older age was associated with a prolonged duration of the apnea period.ConclusionsAll parameters of the SWS could be recorded numerically and objectively using electrphysiological methods. These are similar to those obtained by videofluoroscopic and similar methods. The foreburst activity of the initiation of SWS may represents preparatory activity from the activation of the fast cortical descending motor pathway. Increasing heart rate and the prolonged apnea urged that older people and patients could be carefully tested for respiratory and cardiac rhythm disorders.     

Prevention of ischemic and re-oxygenation arrhythmias and heart fibrillation using the antioxidant ionol

The effect of a synthetic antioxidant, ionol (2,4-ditrebutyl-4-methylphenol) on cardiac arrhythmias induced by 10-minute occlusion of the left coronary artery followed by 5 minutes of reperfusion (RP) was investigated. The study was performed on male Wistar rats, 250-300 g body weight. The animals were ventilated with room air under urethan anesthesia. RP induced more severe ventricular arrhythmias than ischemia (IS). During RP ventricular fibrillation developed in 12 and during IS in 2 out of 24 animals. Other types of arrhythmias--tachycardia and extrasystole--were also more pronounced during RP than during IS. Preadministration of animals with ionol (60 mg/kg, per os) abolished completely ventricular fibrillation during IS and RP. Ionol reduced considerably the incidence of tachycardia and extrasystole, shortening their duration 5-7-fold. The data suggest that the activation of lipid peroxidation may play an important role in the pathogenesis of cardiac fibrillation and open prospects for the prevention and treatment of cardiac arrhythmias with antioxidants.     

The effect of alpha-tocopherol and ionol on the physical structure of the membranes of rat liver microsomes under conditions of antioxidant insufficiency

Physiochemical conformity of the alpha-tocopherol interaction with hepatic microsomal membranes has been studied by means of fluorescent probes (pyrene and 1-anilinonaphthalene-8-sulphonate). The microsomal membrane microviscosity is shown to sharply decrease under conditions of the antioxidant deficiency with vitamin E expelled into animals normalizes microviscosity, but feebly influences the microsomal surface charge. Microcalorimetry has been used to establish that penetration of tocopherol into microsomal membranes was accompanied by the exothermic effect.     

The cholinolytic activity of the new anti-arrhythmia preparation Nibentan]

In the rabbit isolated right atrium and the rat atrial cells, a new class III antiarrhythmic drug Nibentan was shown to exert an anticholinergic effect contrary to Carbachol: the latter decreased the AP duration to 42 +/- 2% of the control whereas Nibentan restored it to 65 +/- 2%. The anticholinergic effect of the drug was found to be due to inhibition of the acetylcholine-activated potassium current: it was decreased by 79 +/- 3% in the rat isolated single atrial cells. In the rabbit isolated sino-atrial node, Nibentan prevented arrhythmogenic effects of vagal stimulation. The new drug may be quite efficient in treatment of flutter and atrial fibrillation.     

Effects of synthetic antioxidant ionol on bioelectric activity of cardiomyocytes and arrhythmia in global ischemia and reperfusion of the isolated rat heart]

Isolated rat hearts were subjected to global ischemia (15 min) and reperfusion (20 min). Transmembrane potentials were recorded on the epicardial surface and contractile force was measured. Ischemia reduced the resting potential, the action potential (AP) amplitude and the AP duration (APD) in control animals. Pretreatment with synthetic antioxidant ionol (BHT, 50 mg/kg, per os) didn't influence the time course of changes in the resting potential and AP amplitude during ischemia, but significantly increased APD. In the pretreated group, 5 min after the aorta clamping, the APD at 50% and 90% levels of repolarization was 36% (p less than 0.05) and 13% (p less than 0.1) higher in comparison to the preischemic level and 10 min after clamping by 27% (p less than 0.1) and 29% (p less than 0.05), respectively. By the end of ischemia in the pretreated group, APD re-decreased almost to basal level, but in control group, it remained decreased. During reperfusion BHT improved the recovery of bioelectrical activity and the contractile function. The BHT 10-fold reduced the malignant arrhythmias duration and 2.5-fold the incidence of ventricular tachycardia and fibrillation during reperfusion. These results indicate that the induced by BHT increase in APD can contribute to the mechanism of BHT antiarrhythmic action.     

An electrophysiological study of parthenogenetic activation in mammalian oocytes

Using conventional electrophysiological techniques, we have investigated the electrical responses of mouse and hamster oocytes in metaphase of the second meiotic division to agents which induce parthenogenetic activation. Oocytes from MF1 mice responded to 8.7% ethanol and to 0.3% benzyl alcohol by a depolarization (sometimes preceded by a brief hyperpolarization). The response to ethanol did not "desensitize," and the membrane potential recovered completely when the exposure to ethanol was interrupted. The response was accompanied by a decrease in membrane input resistance (Rin) and had an equilibrium potential of about +5 mV in standard medium and of -10mV in Na-free medium. The oocytes responded to A23187 and to La3+ by an increased Rin, and usually lysed during or after treatment. Multiphasic responses were elicited by ethanol and by Ca-ionophore in metaphase II hamster oocytes; an early hyperpolarization accompanied by a decreased Rin was a common feature of the response to both activating agents. The early hyperpolarization was no longer elicited when the cells were exposed for a second time to ethanol or A23187. K+ and Cl- were the ions mainly involved in the hyperpolarizing potential elicited by A23187, and K+ (but not Cl-) was the ionic species mainly involved in ethanol response. The above responses were peculiar to metaphase II oocytes since mouse and hamster ovarian oocytes (in prophase I) and fertilized eggs either failed to respond to the activating agents, or responded by increasing Rin. The variety of electrical responses to parthenogenetic agents indicates that in mammalian oocytes parthenogenetic activation is not triggered by a "classical" activation potential.     

An electrophysiological study of olfactory interneurones in the brain of the honey-bee

Discharges of the olfactory units in the brain of the honey-bee were recorded extracellularly. Discharges were excitatory and inhibitory and showed on and on-off responses. In the on responses, phasic, phasic-tonic, and tonic patterns were found. No relation between discharge pattern and the region in the brain was found. The dominant pattern was phasic-tonic in the excitatory and tonic in the inhibitory units. Rebound or long-lasting phenomena seemed to be one of the characteristics of the neurones in the central nervous system.The latency of the response showed that olfactory information entering the deutocerebrum from the antenna was carried to the calyx of the ipsilateral brain via the antenno-cerebral tracts reported by Kenyon (1896), and then to the protocerebral lobe through the stalk of the mushroom body. The information was also carried to the contralateral brain after passing through the calyx of the ipsilateral brain or the central commissure.