The Investigation of the Effects of Melatonin on Electrocardiografic Findings in Rats Undergoing Acute Intense Exercise

Aim:Acute intense exercise causes an additional strain on cardiovascular system. Melatonin has been known as a hormone with cardiovascular protective effects. The aim of this study is to investigate the protective effects of melatonin on cardiovascular changes in rats undergoing acute intense exercise, considering electrocardiogram (ECG) results.Materials and Methods:The 3-5-month-old 28 Wistar albino rats were used in this study and they were divided into 4 groups. The vehicle injection was applied in the control group without any exercise procedure. The groups of exercise, exercise+melatonin (intraperitoneal injection of melatonin at the dose of 10 mg/kg before exercise) and exercise+melatonin+luzindole (intraperitoneal injection of luzindole at the dose of 0.4 mg/kg and melatonin at the dose of 10 mg/kg before exercise) were run on treadmill until they were tired. ECG recording was performed at the end of the exercise.Results:A significant increase in heart rate was observed in both exercise groups. The decreasing effect of melatonin on QT and QTc prolongation in the exercise group was reported; however, this effect did not occur in the luzindol administrated group. Melatonin also decreased corticositerone levels, which increased with exercise, independent of receptor. White blood cell and neutrophile counts of the melatonin administrated group were observed to be close to that of the control group.Conclusion:These results indicate that melatonin can be used as an agent that may decrease unfavorable effects of exercise and improve the quality of exercise

The British public atitude survey regarding inflation and interest rates

The importance of achieving the price stability objective consists in remaining the inflation expectations close to the inflation target in the medium term. As part of its price stability objective, the Bank of England has the task of achieving a 2% inflation target, measured by the annual change in the consumer price index. Regarding these facts, the inflation expectations play a key role in the household and business decision because the inflation expectations are very important for the wage negotiation, and because inflation expectations play an important role in household’s savings decisions. In this article we focus upon the Bank of England / GfK NOP Attitude Survey. The first section deals with some aspects as: the random location, the sample design, the selection of the respondents and the confidence limits for observed survey data. The second section debates the latest trends in household inflation perceptions and expectations. The final section summarizes the public’s attitudes to interest rates and the conduct of the monetary policy.price stability, inflation risk, inflation expectations

QT and QTc prolongation and decreased heart rate after IV administration of levamisole hydrochloride in conscious rabbits

Intravenous doses of 2.5 mg/kg and 5.0 mg/kg of levamisole on RR, QT, QTc (corrected QT), and heart rate in conscious rabbits were evaluated. The study was performed on 14 New Zealand rabbits, 1 year old, weighing between 2.5-3 kg. The animals were assigned to 2 equal groups. Rabbits of groups I and II received via the auricular vein 2.5 mg/kg and 5 mg/kg of levamisole HCl, respectively. Alligator clips were attached to four limbs. ECG records were taken by direct writing electrocardiograph before the study and after 2, 4, 6, 8, 10, 15, and 20 min of the experiment. The QT interval was manually calculated from the beginning of Q wave to the end of T wave. The same leads (II and aVR) were selected for all QT interval measurement. The animals were not given any sedatives or anaesthetics before and during ECG recording. In group I, two rabbits had the second degree atrial block at the 2(nd) and 4(th) min after the injection, which disappeared later. Heart rates were 216-230 beats/min at min 0 and dropped to 193-210 beats/min at the 2(nd) min after the injection in both groups, and remained low throughout the study. Heart rates of both groups taken at 2, 4, 6, 8, 10, 15, and 20 min after the injection were significantly lower than the values taken at 0 min except for the values of the 15(th) min in group II. QT and QTc prolongation was noticed in both groups when compared to 0 min values. Although we have no solid data to explain the mechanism involved in bradycardia and atrial block provoked by levamisole, its use resulted in bradycardia, second-degree atrial block, and acute prolongation of QT and QTc in conscious rabbits

QT interval prolongation and decreased heart rates after intravenous bolus oxytocin injection in male and female conscious rabbits

The aim of this study was to evaluate changes in heart rate (HR), QT and RR intervals and corrected QT (QTc) values in conscious male and female New Zealand rabbits which intravenously received oxytocin (OXT) at different dosages. Animals were divided into 6 equal groups: group I (n = 6 male, received 0.75 U OXT per animal); group 11 (n = 6 male, received 1.5 U OXT per animal); group III (n = 6 male, received 3 U OXT per animal); group TV (n = 6 female, received 0.75 U OXT per animal); group V (n = 6 female, received 1.5 U OXT per animal); group VI (n = 6 female, received 3 U OXT per animal). ECG recording were taken from all animals before injection and then at 2, 4, 6, 8, 10, 15 and 20 min of OXT administration. QT and RR intervals obtained at 2 min of OXT administration were significantly prolonged in all groups (p < 0.05) with one exception that is the 1.5 U OXT injected female group where only QT interval did not change. The prolongation of QT and RR intervals persisted for 20 min in 1.5 U OXT injected male group while only QT interval prolongation was obvious for 20 min in 3 U OXT injected female group as for the other groups the prolonged interval were observed for 8-10 min and then returned to baseline values. Generally, a significant prolongation of QTc was noticed in both male and female rabbits at the 2 and 4 min in all groups and bradycardia was noticed at 2 min of OXT administration in all groups. Heart beats returned to normal values in all groups after 8 min of OXT administration. The change of HR, RR, QT and QTc was gender- but not dose-dependent (p < 0.001). The male rabbits were more sensitive to OXT effect then female rabbits. In conclusion, OXT used in therapeutic dosages decreased heart rate and prolonged QT and QTc intervals. Although cardiovascular effect of OXT are of short duration, its use in patient with risk factors for malignant arrhythmias requires more attention

Effects of xylazine, medetomidine, detomidine, and diazepam on sedation, heart and respiratory rates, and cloacal temperature in rock partridges (Alectoris graeca)

In this study, heart and respiratory rates, cloacal temperature, and quality of sedation were evaluated before (0 min) and after (10, 20, and 30 min) i.m. administration of xylazine (10 mg/kg; n = 7), medetomidine (75 mu l; n = 6), detomidine (0.3 mg/kg; n = 6), or diazepam (6 mg/kg; n = 7) in rock partridges (Alectoris graeca). All partridges recovered from sedation without any disturbance. Xylazine and diazepam administration did not induce significant changes in heart rate, which did decrease significantly after medetomidine and detomidine administration (P < 0.001). Mean respiratory rate was decreased dramatically at 20 and 30 min after xylazine (P < 0.001) and medetomidine (P < 0.005) administration, and at all stages of sedation after detomidine injection (P < 0.001), whereas there was not any significant change after diazepam injection. In all groups, cloacal temperature measured at 10, 20, and 30 min tended to decrease compared with baseline values. Sedative effects of the drugs started within 2.1 +/- 0.2 min for detomidine, 2.6 +/- 0.4 min for diazepam, 3.1 +/- 0.4 min for xylazine, and 4.8 +/- 0.8 min for medetomidine application. There was an extreme variability in time to recovery for each drug: 205 +/- 22.2 min for xylazine, 95 +/- 12.2 min for medetomidine, 260 +/- 17.6 min for detomidine, and 149 +/- 8.3 min for diazepam. In conclusion, xylazine, medetomidine, detomidine, and diazepam produced sedation, which could permit some clinical procedures such as handling and radiographic examination of partridges to occur. Of the four drugs, xylazine produced stronger and more efficient sedation compared to the others, which could permit only minor procedures to be performed. However, depending on the drug used, monitoring of heart and respiratory rates and cloacal temperature might be required