@2024 Afarand., IRAN

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ISSN: 2252-0805    The Horizon of Medical Sciences 2016;22(3):209-214

Background
Cardiac ischemia includes a series of molecular and cellular events which leads to the progressive weakness of heart muscle and eventually heart failure and death [1].
Previous Studies
... [2-6]. Beta-hydroxy-beta-methyl butyric acid or beta-hydroxy-beta-methyl butyrate-briefly called HMB- is a metabolite of leucine amino acid (an essential amino acid) which of course is made in the body of human and animals [ 7]. Several biochemical studies have shown that HMB is the precursor of cholesterol and a halt in cholesterol synthesis in the muscle using drugs can lead to muscle damage, diminution of muscle cell`s function and its even death [7]. ... [8-17].
Aim(s)
This study aimed to investigate the preventive effects of beta-hydroxy-beta-methyl butyrate (HMB) on ventricular arrhythmias caused by ischemia in rats.
Research type
This study is experimental.
Research society, place and time
30 male Wistar rats were studied.
Sampling method and number
30 male Wistar rats with the weight range of 200 to 250 grams were provided from Experimental Medicine Research Center of Birjand University of Medical Sciences. These rats were kept in stable physical conditions of the animal home with a temperature of 22± 2 °C and a 12-hour cycle of light and darkness. They had free access to standard food and drinking water.
Used devices&materials
Animals were randomly divided into three groups (10 in each group); group 1 was the control group which had orally received normal saline by gavage, and groups 2 (HMB320) and 3 (HMB700) which were orally administered HMB (Karen Pharmaceutical and Vital Dietary Supplements; Iran) at a dose of 320 and 700 mg per kg using gavage, respectively. After 2 weeks of treatment and being weighted the rats were anesthetized intraperitoneally by a combination of 100 mg per kg ketamine (Rotex Medica; Germany) and 8 mg per kg xylazine (Alfasam; Netherlands). After intubation, the endotracheal tube was inserted and attached to the ventilator mechanically (70 beats per minute, 1 ml per 100 g of body weight of tidal volume). Body temperature was monitored by a thermometer through rectal probe and was controlled using a thermal mat in the temperature range of 37 ±1 ° C. To continuously record the electrocardiogram, lead II subcutaneous needle electrodes were used which were attached to the transducer (Gain couplers). The left carotid was cannulated through the cervical gap and was attached to the stabilization device by the pressure transducer (strain gauge coupler) (NarcoBiosystem; USA). Through the gap, the fourth intercostal appeared at the left side of the heart and the 0-5 silk suture was passed under the left anterior descending coronary artery (LAD). In this case, after 15 minutes of stabilization phase the left ventricle was under ischemia for 30 minutes with the tying thread. The resulting electrocardiogram was interpreted separately for each rat based on Lambs protocol criteria [18]. Variables of the number of premature ventricular contractions (PVC), time duration of ventricular tachycardia (VT) and ventricular fibrillation (VF) were measured during the 30 min ischemia and the results obtained from studying electrocardiogram and the curve of arterial blood pressure were matched to eliminate errors caused by stabilization devices. Data were presented as statistical means and were analyzed using SPSS 16 software. First the normality of data distribution was evaluated using the Kolmogorov-Smirnov test. Then to compare the means of the numbers of premature ventricular contractions (PVC), time duration of ventricular tachycardia (VT) and ventricular fibrillation (VF) between the studied groups, Kruskal-Wallis test was employed and for comparing the mean of percent change in blood pressure of carotid artery in rats at the end of ischemia phase, ANOVA and Tukey's subsequent test were used according to the basic conditions. Besides, rate of death during the ischemic phase between groups was examined by chi-square test.
Findings by Text
The mean number of PVC in group 2 (receiving the dose of 320 mg per kg) and group 3 (receiving the dose of 700 mg per kg) had a significant reduction compared to the control group (p=0.001). The mean number of PVC in group 3 was significantly less than group 2 (p=0.008). Furthermore, the mean duration of VT in groups 2 and 3 indicated a significant decrease compared with the control group (p=0.001), while the difference was not significant between groups 2 and 3 (p=0.924). Difference between the mean duration of VF in group 2 and the control group was not significant (p=0.360), while it was less and significant in group 3 compared with the control group (p=0.003). This statistical comparison between groups 2 and 3 was not significant (p=0.053). The difference between the mean of the percent of blood pressure changes in carotid artery in rats at the end of ischemia phase was significant according to the basic conditions in group 3 compared with the control group (p=0.001). A significant difference was observed between groups 2 and 3 (p=0.001), but such a difference was not observed between group 2 and the control group (p=0.717; Table 1). 3 rats in the control group and only one rat in other groups died during the ischemic phase and the rate of death was not significantly different between groups during the ischemic phase (p>0.05).
Main comparison to the similar studies
In a study, Raymond et al. demonstrated that this combination will have an anti-inflammatory role after an intense activity, so it can also be regarded as an antioxidant [12]. ... [19, 20] Chausdhuri et al. have expressed the role of insulin in an acute inflammatory process of cardiac ischemia as anti-inflammation and even profibrinolytic [21].
Suggestions
For further investigation it is recommended to do the experiment in a longer period with different doses of HMB and to compare the effects of this supplement with drugs that have confirmed effects in this field in terms of increased levels of the enzyme, electrical changes and other related variables to tissue damage. It is also suggested to separately examine the long-term impacts of this drug in reducing the side effects after myocardial ischemia and consequently cardiac structural changes.
Limitations
The death of rats during the operation can be one of the limitations of this study leading to a decrease in the sample size. Besides, preparing the necessary drug was another problem of this program. In this study, investigating the events at the cellular level and enzyme levels was not possible and in case of doing so, commenting on the effects of this compound could have been more certain.
Conclusions
Preventive use of HMB supplementation with the minimum dose of 320 mg per kg in 2 weeks can probably have a significant effect on reducing the numbers of PVC dose-dependently and decreasing the time duration of VT and VF dose-independently as the acute effects of ischemic.
Acknowledgments
Many thanks are regarded to the Karen Pharmaceutical and Vital Dietary Supplements Company for donating HMB compound and to the Experimental Medicine Research Center of Birjand University of Medical Sciences for their cooperation and supports.
Conflict of interest
Non-declared
Ethical Permissions
The principles of working with laboratory animals are according to the ethical guidelines which have been approved by the Ethics Committee of the University's Research Department.
Funding Sources
The expense of this study has been afforded by the Research Department of Birjand University of Medical Sciences as a research project with the code of 1035.

TABLES and CHARTS

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