A comparative study on the equine and camelid antivenoms upon cardiovascular changes induced with Hemiscorpius lepturus venom in rats

Objective(s): In this study, the neutralizing abilities of the equine and the recently introduced camelid antivenoms on the hemodynamic parameters (inotropism, chronotropism, and arrhythmogenicity) were assessed following envenomation by Hemiscorpius lepturus venom in rats. Materials and Methods: At first, the electrophoretic profiles of both products were obtained by using the SDS-PAGE method (12.5%) and stained with Coomassie blue and silver nitrate. Secondly, different doses of the camelid antivenom (10, 50, and 100 μl) were given intravenously in 10 min before venom injection (400 μg/rat). The neutralizing potencies of camelid and equine antivenoms were measured by preincubation (100 μl) with H. lepturus venom for 30 min at room temperature. Finally, equal amounts of the antivenoms were injected intravenously to observe the hemodynamic changes. Results: Based on the electrophoretic profile, it was evident that undesired proteins significantly decreased in equine antivenom, owing to impurities. Pretreatment with the camelid antivenom (100 μl), neutralized the elevation of the mean arterial pressure evoked with scorpion venom injection (88.15±4.56 versus 10.2±1.23 percent at the 8th min). The Incubation of the venom and the camelid antivenom counteracted the hemodynamic changes, but the equine product had no effect. The intravascular injection of the equine antivenom transiently increased the mean arterial pressure as compared to the control (108.67±8.63 mmHg versus 52.67±1.93 mmHg at the 10th min). Conclusion: The most obvious finding emerging from this study was that the camelid antivenom neutralized the hemodynamic changes in rats significantly, but in comparison, the equine antivenom had just a minor ability

Hemodynamic changes in experimentally envenomed anaesthetized rats by intravenous injection of Hemiscorpius lepturus venom

Background: We investigated the hemodynamic changes (Inotropic, chronotropic and arrhythmogenic) in intrave-nously envenomed anesthetized rats with Hemiscorpius lepturus venom. The neutralizing potencies of different drugs and commercial antivenom were assessed simultaneously. Methods: Different doses of the crude venom (100, 200 and 400μg/rat) were injected during five minutes via the femoral vein and cardiovascular changes were recorded in rats in Razi Institute Corporation, Karaj, Iran in 2017. The drugs (Atropine, lidocaine, propranolol and prazosin) were injected before the venom for determination of the coun-teracting effects. Different volumes (100, 500 and 1000μl) of the antivenom were pre envenomed to neutralize cardi-ovascular changes. Results: Temporary hypertension and bradycardia with no arrhythmogenic effects were depicted within twenty minutes. There was a difference in arterial pressure between the venom (400μg/rat) and the vehicle at 8 minutes (114.68±5.1mmHg versus 70.2±4.3mmHg). Elevation of the mean arterial pressure was inhibited by propranolol (2 mg/kg) and neutralized by prazosin (1mg/kg) while lidocaine (4mg/kg) and atropine (1mg/kg) had no effects. Pre-medication with Iranian commercial antivenom (1000μl) produced surprisingly temporary hypertension compared to the vehicle (140.84±4.5 versus 84.3±3.2). It had no neutralizing properties on blood pressure variation before the venom injection. Volume-expanded hypertension phenomenon was ruled out in a parallel study. Conclusion: This venom has vasoconstrictive effects in rats probably due to the presence of norepinephrine like ma-terials in its content or liberated from adrenal gland inhibited by prazosin premedication. The neutralizing effects of antivenom on venom-induced hypertension are questionable. © Tehran University of Medical Sciences