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1.
烟碱受体(nAchRs)是一种由α与β亚基所组成的同源或异源五聚体,已有研究表明心脏内含有nAChRs。为确定何种nAChRs亚基在烟碱(Nicotine)对心脏的影响中起主要调节作用,本试验利用大鼠模型进行药物试验。在给大鼠注射100μmol/L烟碱后,起初引起大鼠短暂的心率降低-7次±2%,随之出现大幅度的心率增加17次±5%,增加的心率在10 min~15 min恢复正常。烟碱引起心率的降低作用能被α7亚基特异性阻断剂α-金环蛇毒素(-αBTX,100 nmol/L)所抵消;相反,心率的增加现象在α-金环蛇毒素存在时得到延续。选择性β4亚基竞争剂金花雀碱(Cytisine)对大鼠进行注射后,结果与烟碱对大鼠心率作用的结果相似,因此在心脏交感神经末梢可能存在nAChRsβ4亚基。试验结果,显示不同的nAChRs亚基在对烟碱对心脏的作用中起不同的调节作用,更多药理试验结果显示,α7亚基在对烟碱引起心率降低的调节中起主要作用,β4亚基则在心率的增加过程中起主要作用。 相似文献
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旨在观察不同剂量盐酸椒苯酮胺(piperphentonamine hydrochloride,PPTA)对新西兰兔心电图QT间期(从QRS波开始到T波结束时的时限)的影响。将40只新西兰兔随机分为5组,每组8只,分别为溶剂对照组(5%葡萄糖)、PPTA低(2.5mg/kg)、中(10mg/kg)、高(25mg/kg)剂量组以及阳性对照组(9mg/kg索他洛尔),采用体表心电图技术,通过Pclab-530C生物医学信号采集处理系统记录各组新西兰兔注射相应药物后PPTA标准肢体Ⅱ导联心电图变化。结果表明,2.5mg/kg、10mg/kg PPTA在缓慢给药后不引发QT间期延长,25mg/kg PPTA在缓慢给药后15min内引起QT间期轻度延长(P0.05);PPTA对QT间期的影响主要发生在给药后0~15min,45min后基本恢复正常。因此,低、中剂量盐酸椒苯酮胺(PPTA)不引发新西兰兔心电图QT间期延长,安全性较高,高剂量可能有引发QT间期延长风险,提示在临床用药时需要注意药物使用剂量,以防QT间期延长和心律失常的发生。 相似文献
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为了观察黄芪注射液对正常犬和二尖瓣关闭不全病理模型 (MR)犬的变时作用 ,并探讨其机制 ,在异氟烷吸入麻醉下 ,对正常及外科方法制作的犬亚急性二尖瓣关闭不全模型 (术后 5 0天后 )一次性静脉推注含生药 2 g/ m L的黄芪注射液 1 .2 5 m L/ kg,通过体表心电图测定心率和 PQ、QRS、RR、QT,并计算 QTC(QT/ RR)间期。在正常犬 ,开始注射黄芪注射液后 ,心率出现先减少后恢复再持续减少和显著变化。 MR模型犬开始注射液后 ,心率出现先升高后恢复再持续升高的显著变化。 MR模型犬的心率减慢变化与 RR、PQ、QT、QTc呈高度显著负相关 (P<0 .0 1 )。表明黄芪注射液对正常比格犬 ,具有加快心率的正性变时作用。对二尖瓣闭锁不全 (MR)模型犬具有减缓心率的负性变时作用。黄芪注射液的变时作用似与机体的机能状态有关 ,呈现双向调节作用。 相似文献
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β-兴奋剂,全称β-肾上腺素能兴奋剂或β-肾腺素能受体激动剂,也有称能量重分配剂。它是一化学结构和生理功能类似肾上腺素的苯乙醇胺类生物,能与动物体内大多数β-肾上腺素能受体结,激发β-肾上腺素能受体兴奋的药物。β-兴奋剂影响营养物质在动物体内的流向和重新分配,有促进肌肉组织生长,降低胴体脂肪含量,提高瘦肉和增加瘦肉产量,因而曾在欧美广泛使用;但另一面,能与细胞表面的β-受体结合产生明显的生理用,如心悸、头疼、目眩、恶心、呕吐、发烧、战粟、神过敏、血管扩张、心率加快、肌肉震颤等,而且β-奋剂残留会聚集在动物可食用组织… 相似文献
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对60条不同年龄的藏獒在清醒状态下进行了12个导联的心电图测定,建立了心电图基本数据。结果发现,被检健康藏獒皆为正常窦性心律,是生活在青藏高原动物的共同特性,青海藏獒的总体心率为(108±6)次/min,R-R间期时限为(0.558±0.035)s,心电轴皆正常不偏移,青海藏獒不同年龄间心电图差异不显著(P0.05);心率随年龄的增加逐渐变缓,且年龄与P-R间期的时限成正相关,反之则缩短,不同年龄的藏獒QRS波群均无明显差异(P0.05)。 相似文献
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通过对西藏小型猪心电图分析,寻求西藏小型猪心电图变化的规律,并与人类和贵州小型猪心电图进行比较,以期为西藏小型猪实验动物化提供心电图基本资料。用ECG-9020K心电图仪,描记完全清醒状态的西藏小型猪45头,选择Ⅰ、Ⅱ、Ⅲ标准导联和aVR、aVL、aVF单极加压肢体导联的心电图。结果显示:①心电图均为窦性心率;②P波在Ⅰ、Ⅱ、aVF导联均为直立,在Ⅲ、aVL导联大部分直立,在aVR导联均倒置;③QRS综合波形在Ⅰ导联以qR为主,Ⅱ导联以qRs、Rs为主,Ⅲ导联以Rs、qRs为主,aVL导联以qRr、sr’和qr为主,aVR导联以rsr’、Qr和Q为主,aVF导联以Rs和qRs为主;④T波在Ⅰ、Ⅱ、Ⅲ、aVF导联中多为直立,在aVL、aVR导联中多为倒置;⑤各波间期时间(ms):P波(68.18±23.54),P-R间期(92.69±20.64),QRS间期(47.76±13.50),Q-T间期(225.93±45.03),Q-Tc间期(225.47±31.23)。西藏小型猪心电图特征与人心电图基本相似,但心率较快,P-R间期、QRS间期、S-T间期和Q-T间期较短及T波方向变化大;西藏小型猪心电图特征与贵州小型猪心电图很相似,但Q-T间期较贵州小型猪短。 相似文献
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Shimamura S Endo H Kutsuna H Kobayashi M Hirao H Shimizu M Tanaka R Yamane Y 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2006,68(3):213-217
Recent studies have demonstrated the benefits of nitric oxide (NO) on myocardial hypertrophy and myocardial fibrosis. It was suggested that NO has a protective effect on myocardial cell through the neurohormonal system. This effect serves to highlight the important role of NO in maintaining the function and form of heart with chronic heart failure. However, there are no known reports about on the effect of prolonged administration of nitrate on pressure over-load heart. This study was conducted to examine the long-term effect of oral nitrate therapy in rats with pressure-overloaded heart. An abdominal aorta constricted (AC) model of pressure-overloaded heart was created in male Wistar rats. Sustained release isosorbide dinitrate (sr-ISDN) (5 mg/kg once a daily) was administered to the rats once a daily for 12 weeks. The animals were euthanized during the study period, and the heart was collected and weighed. Histopathological examination was performed to evaluate the effect of sr-ISDN on myocardial hypertrophy and fibrosis. The ratio of heart to body weight increased significantly in AC rat and this increase was significantly prevented by sr-ISDN treatment. Histopathological examination showed significant increase in fibrotic area of AC rat compared to sham rat, this increase was inhibited by sr-ISDN treatment. Cardiomyocyte transverse diameter was significantly increased in AC rat compared with sham rat, but this increase tended to decrease by sr-ISDN treatment. In conclusion, intermittent administration with sr-ISDN has mild effect in inhibiting cardiac hypertrophy and marked effect in inhibiting fibrosis due to pressure-overload. 相似文献
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Koyama H Yoshii H Yabu H Kumada H Fukuda K Mitani S Rousselot JF Hirose H Uchino T 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2004,66(9):1107-1111
Comparison of the QT interval and corrected QT interval values that were calculated by the methods of Bazett (QTc1) and Fridericia (QTc2) were made between dogs with or without cardiac diseases to determine the influence of the QT interval on canine heart failure. Upon comparison of the measured values on ECG between the cardiac disease and non-cardiac disease groups, it was observed that the heart rate(HR) was significantly higher in the cardiac disease group than in the non-cardiac disease group, although the QT interval was similar in the two groups. The QTc1 and QTc2 were significantly longer in the cardiac disease group than in the non-cardiac disease group. With the progression of the New York Heart Association Class, the HR tended to increase. The QTc1 and QTc2 became significantly prolonged with the progression of heart failure. Nevertheless, because Bazett's correction formula is known to overcorrect when the HR is high, it was considered that the QTc1 was actually overcorrected by high HR with the progression of heart failure. The QTc2, on the other hand, was only slightly influenced by HR, suggesting that the prolongation was due to the progression of heart failure. These results suggest that the prolongation of QTc2 in cardiac disease reflects the substantial prolongation of the QT interval without the influence of HR. It is suggested that the QTc2 could be a useful parameter for assessing the degree of heart failure in dogs with cardiac disease. 相似文献
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OBJECTIVE: To develop a clinically useful model for predicting QT interval duration as a function of heart rate in healthy cats. ANIMALS: 20 healthy cats. PROCEDURE: For all cats, results of a physical examination, electrocardiography, and echocardiography were normal. Twenty-four hour heart rate and rhythm data were collected by means of ambulatory electrocardiography. Hourly ECG segments were obtained from the 24-hour recordings. Mean heart rate and the mean of 5 QT interval measurements were calculated for each of 479 usable ECG segments. Analysis of covariance was used to develop models to describe variability in QT interval duration. RESULTS: Prediction equations (R2 = 0.81) including terms for heart rate, (heart rate)2, age group (1 to 4 vs 8 to 14 years old), and their interactions were developed. Sex, individual cat, and time of day were of little value in predicting QT interval duration. A simplified prediction equation without age group (R2 = 0.71) also was developed and had better predictive ability than reported correction formulas for QT interval duration. CONCLUSIONS AND CLINICAL RELEVANCE: Prediction equations with 95% prediction intervals for expected QT interval duration in healthy cats were generated. Abnormal QT interval duration can be associated with cardiac electrical instability, yet QT interval duration is greatly influenced by heart rate. Results of the present study provide reference ranges for expected QT interval duration as a function of heart rate in healthy cats. 相似文献
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Comparison of the effects of thiopentone and propofol on the electrocardiogram of dogs 总被引:1,自引:0,他引:1
Sixty-four dogs were randomly assigned to receive either thiopentone or propofol and their electrocardiograms were recorded immediately before and shortly after they were anaesthetised. Thiopentone caused a marked increase in QT and JT intervals, a flattening of the T-wave and an increase in precordial QT dispersion. Propofol induced a less marked increase in QT and JT intervals, corrected for heart rate. Both agents induced an increase in heart rate and a decrease in heart rate variability, consistent with reduced vagal tone. Shortly after anaesthesia was induced, thiopentone affected ventricular repolarisation to a far greater extent than propofol, changes which suggest that it may be more likely to induce re-entrant ventricular arrhythmogenesis and could be associated with an increase in sympathetic tone. Propofol may therefore be more suitable than thiopentone for dogs with a susceptibility to ventricular arrhythmias or a long QT interval. 相似文献
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Masanao Yokohira Yuko Nakano Nozomi Hashimoto Keiko Yamakawa Fumiko Ninomiya Sosuke Kishi Kousuke Saoo Katsumi Imaida 《Journal of toxicologic pathology》2012,25(4):257-263
In vivo, nicotine in cigarette smoke induces various effects not only on the
respiratory system but also the central and peripheral nerve systems, circulatory organs and
digestive organs, and there is a possibility of promotion of lung tumorigenesis. The present
experiment was conducted to examine histopathological changes caused by nicotine in the lung
with repeated intratracheal instillation (i.t.). Six-week-old male F344 rats were administered
nicotine by i.t. at doses of 0.05, 0.1 and 0.2 mg nicotine/rat every 3 weeks beginning at week
4, for up to a total of 9 times and were then sacrificed at week 30. The total number of
administrations, total dose of nicotine and effective number of rats were 9 times, 0.45 mg and
5 rats and 4 times, 0.20 mg and 5 rats for the 0.05 mg nicotine/rat group; 3 times, 0.30 mg and
5 rats and 4 times, 0.40 mg and 3 rats for the 0.1 mg group; and 3 times, 0.60 mg and 3 rats
for the 0.2 mg group, respectively. As a control group, 5 rats were administered 0.2 ml
saline/rat 9 times. Some rats administered 0.1 and 0.2 mg nicotine suffered convulsions just
after administration. Histopathologically, though proliferative changes were not observed,
neutrophil infiltration, edema and fibrosis in the lung were induced by nicotine. In
conclusion, repeated treatment of nicotine promoted neurologic symptoms in the acute phase, and
strong inflammation in the lungs in the chronic phase, even at a low dose. Toxicity of nicotine
is suggested to depend not on total dose of nicotine in the experiment but rather on repeated
injury with consecutive administration. 相似文献
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不同比例虫草培养基混合料对SPF级Wistar大鼠主要脏器重量及其系数的影响 总被引:1,自引:1,他引:1
为探讨不同比例的虫草培养基混合料对SPF级Wistar大鼠主要脏器重量及脏器系数的影响,用电子天平测定3组动物的体重、心、肝、脾、肺、肾、肾上腺、睾丸、卵巢和胃的重量,并计算其脏器系数。结果表明,不同比例组的同性别Wistar大鼠,其体重之间不存在显著差异;低比例组雄性Wistar大鼠心脏、肺脏和睾丸,雌性Wistar大鼠肺脏的重量显著或极显著高〖JP2〗于对照组、高比例组;低比例组雄性Wistar大鼠心脏、肺脏、肾脏和睾丸,雌性Wistar大鼠心脏、肝脏、肺脏、肾脏和胃的脏器系数显著或极显著高于对照组、高比例组;低、高比例组Wistar雄鼠和高比例组Wistar雌鼠的肾上腺重量及其系数均显著低于对照组。可见,适当比例的虫草培养基可以作为啮齿类试验动物的添加料,但是否适用于饲喂其它动物还有待于进一步的试验研究。 相似文献
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The influence of the simultaneous administration of monensin and tiamulin on the motor nerve conduction velocity and the refractory periods of the N. ischiadicus was studied on 4-week old cockerels. The combined administration of the two substances resulted in significant decrease of the conduction velocities of the peripheral nerve, while the relative and absolute refractory periods were seen to increase significantly as a result of the medications. The observed alteration of the peripheral nerve function in the early phase can already attribute to the development of the serious clinical signs of the toxic interaction. The simultaneous application of monensin and tiamulin caused also changes in the electrocardiogram which was expressed in a prolongation of the RS interval and the ST segment. At the same time the heart rate was reduced. 相似文献
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S A Youssef A Ramadan N A Afifi M D Aziz 《DTW. Deutsche tier?rztliche Wochenschrift》1991,98(2):56-60
Haemodynamic effects of sodium taurocholate (S.T.) were studied on isolated guinea pig's auricles, rabbit's heart, rabbit's aortic strip, guinea pig's tracheal chain as well as the blood pressure and ECG pattern changes in pentobarbital anaesthetized dogs. S.T. induced significant negative inotropic and chronotropic effects on the isolated auricles of guinea pig's especially in higher concentrations. Using isolated rabbit's heart, the negative inotropic and chronotropic effects induced by S.T. were found to be depending on the concentration. Cardio-inhibitory actions of the salt are not due to either cholinergic beta 1-adrenergic blocking effect or nicotine like activity. S.T. in all tested concentrations had no effect on the contractile response of isolated rabbit's aortic strip or guinea pig's tracheal chain and did not prevent the contractile response induced by noradrenaline and histamine. In anaesthetized dogs, i.v. injections of the salt in a dose of 30 mg/kg b. wt. produced a significant decrease in systolic and diastolic pressure, but lower doses induced no significant changes. A dose of 30 mg/kg b. wt. of the salt potentiates the decrease in systolic and diastolic pressure when coadministered with the neuromuscular blocking agent, atracurium besylate. Atropine, propranolol and phentolamine did not alter the hypotensive effect of S.T. (neither cholinergic nor beta 1-adrenergic blocking effect). The electrocardiographic pattern induced by S.T. (20-30 mg/kg b. wt.) in dogs were mainly characterized by decrease in heart rate and prolongation of P-T interval. 相似文献
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Current concepts in vasodilator therapy for advanced or refractory congestive heart failure 下载免费PDF全文
Miller MS O'grady MR Smith FW 《The Canadian veterinary journal. La revue veterinaire canadienne》1988,29(4):354-361
The use of vasodilators to assist in the management of advanced heart failure has gained widespread acceptance in human cardiology. The early experience with these same drugs in the management of heart failure in domestic animals has similarly been encouraging.Vasodilators function to favorably alter preload and afterload in the heart failure setting. Venodilators can resolve pulmonary edema by reducing an elevated left heart preload. Arterial vasodilators can increase stroke volume, reduce an elevated preload, and blunt or abolish the stimulation of the harmful compensatory measures that are induced in the presence of heart failure. Both classes require careful monitoring to ensure that marked hypotension does not occur.Vasodilator therapy can significantly complement other traditional modalities of drug therapy in cases of advanced heart failure. 相似文献