Comparative study of the venoms from three species of bees: effects on heart activity and blood

Crude venoms from three highly evolved aculeate species: Apis mellifera (highly social bees), Bombus morrisoni (eusocial bees), and Anthophora pauperata (solitary bees), were used for conducting this study to compare the effects of honey bee, bumble bee, and solitary bee venom on toad cardiac muscle activity. In addition, these venoms were tested on rat whole blood in order to determine their ability to induce red blood cell haemolysis. The main toxic effects on isolated toad heart were monitored by ECG after perfusion with different concentrations of each bee venom, and are represented as a decrease in the heart rate (HR) accompanied by an elongation in the P-R interval. A gradual and progressive increase in R-wave amplitude was also noted. Several electrocardiographic changes were noted 5-30 min after envenomation with any of the bee venoms. The mechanism of action of the three bee venoms was determined by direct application of atropine, nicotine, or verapamil to the isolated toad hearts. Comparison of the three venoms revealed that Anthophora pauperata venom is the most effective venom in inducing bradycardia, and it has the strongest negative dromotropic effect. Apis mellifera venom demonstrates the most positive inotropic effect of the three venoms. The effects of bee venom on the blood indices of erythrocyte osmotic fragility (EOF) and plasma albumin levels were studied after incubation of rat blood with each venom. It was noticed that RBCs decreased while Hb content, HCT, MCV, MCH, and MCHC increased, although this change did fluctuate and was not significant. A nonsignificant decrease in EOF was noted after 60 min with any of the venoms used. Incubation of rat whole blood with 1 microg/ml of any of the bee venom solutions revealed a highly significant decrease in plasma albumin levels. It can be concluded that venoms from the three species of bees we tested have negative chronotropic and dromotropic effects on isolated toad heart, with Anthophora pauperata being the most potent. In addition, the venoms have positive inotropic effects withApis mellifera being the most potent. The nonsignificant effects of venom on blood profiles and erythrocyte osmotic fragility, combined with the significant decrease in plasma albumin level suggest a protective effect of plasma albumin against bee venom induced toxicity to erythrocytes.