Effects of oral honey administration on ischemia reperfusion -induced arrhythmias and infarct size in isolated rat heart

Abstract

Introduction: Honey is widely used in folk-medicine throughout the world. However, it has a limited use in modern medicine due to lack of scientific support. Honey has demonstrated antimicrobial properties. High antimicrobial activity is as a result of osmotic effect, acidity, hydrogen peroxide and phytochemical factors, and as yet unidentified compound putatively described as inhibines, although lethality of and inhibition by these and other components against microorganisms vary greatly, depending on the floral source of nectar. Honey has been reported to have an inhibitory effect to around 60 species of bacteria including aerobes and anaerobes, gram-positives and gram-negatives. An antifungal action has also been observed for some yeasts and species of Aspergillus and Penicillium, as well as all the common dermatophytes. Honey has antioxidant activity. In general, the antioxidant capacity of honey appeared to be a result of the combined activity of a wide range of compounds including phenolics, peptides, organic acids, enzymes, Maillard reaction products, and possibly other minor components. The phenolic compounds contributed significantly to the antioxidant capacity of honey but were not solely responsible for it. There is no report regarding cardioprotective effects of chronic oral administration of natural honey against ischemia/reperfusion (I/R) injuries. Therefore, in this thesis, effects of chronic oral honey on I/R- induced cardiac arrhythmias and infarct size were investigated in isolated rat heart.

Materials and Methods: Male Wistar rats weighing 270-300 g were divided into four groups (n=10 in each group) and fed with different concentrations of honey (1%, 2% and 4%) for 45 days except the control group. After anesthesia by sodium pentobarbital (60 mg/kg, i.p.), the hearts were excised rapidly and mounted on a Langendorff apparatus under 100 mmHg pressure at 37 °C and perfused throughout the experiments with modified Krebs-Henseleit (K/H) solution. A fluid filled balloon introduced into the left ventricle and inflated to give a preload of 8–10 mmHg. After 20 min stabilization, the hearts subjected to 30 min regional ischemia followed by 120 min reperfusion. An epicardial ECG was recorded by a polygraph during the experiment. Based on the Lambeth conventions, the ECGs were analyzed to determine cardiac arrhythmias. At the end of reperfusion, Evans blue solution was infused to stain the non-ischemic area. Then the hearts were cut into slices, incubated by 1% thriphenyl tetrazolium chloride solution, and fixed in formalin. The infarct size was determined by using a computerized planimetry package.

Results: Administration of oral honey (1% and 2%) reduced infarct size from 23±3.1% (control) to 9.7±2.4 and 9.5±2.3%, respectively (p<0.001). In the ischemic phase, administration of oral honey (1% and 2%), was reduced the number of VT from 473±166 in the control group to 26±14 (p<0.01) and 72±54 (p<0.05), respectively. Duration of VT was decreased by the same concentrations (p< 0.01 and p<0.05, respectively). Honey (1% and 2%) also led to a reduction in the number of ventricular ectopic beats (VEBs) from 941±224 (control) to 421±143 and 241±116 (p<0.05 and p<0.01), respectively. Duration and incidence of reversible ventricular fibrillation (Rev VF) were decreased statistically significant by honey 2% (p<0.05). In addition, honey (1% and 2%) caused significant reduction in the incidence of VT and total VF compared to the control group (p<0.05). During reperfusion time, VT incidence was 73% in the control group, however natural honey (1%) decreased it to 22% (p<0.05). In addition, total VF incidence, time and number of VT were decreased significantly by the same concentration (p<0.01). In addition, Rev VF incidence was lowered significantly from 82% (control) to 33% by 1% and 2%, respectively (p<0.05).

Discussion and Conclusions: For the first time, results of present study demonstrated protective effects of chronic oral honey administration against ischemia/reperfusion injuries in isolated rat heart as reduction of infarct size and arrhythmias. Maybe, antioxidant activity, the existence of various components especially important minerals, energy sources such as glucose and fructose and some improvement in hemodynamic functions may have important roles in these protective effects.