The role of propranolol and atropine in mitigating the toxic effects of scorpion venom on rat electrocardiogram

Dose-dependent serum biochemical alterations in Wistar albino rats after Palamneus gravimanus (Indian black scorpion) envenomation

Palamneus gravimanus envenomated rats showed dose-dependent alterations in serum biochemical parameters. Sub lethal doses of 100, 200, and 400 microg/kg of P. gravimanus venom were injected intramuscularly into rats. Blood samples were collected by heart puncture before and 4 h after crude venom administration. Serum was analyzed for glucose, blood urea nitrogen (BUN), uric acid, total protein, cholesterol, sodium, potassium, inorganic phosphorus, alkaline phosphatase, aspartate aminotransferase (AST-SGOT), alanine amino-transferase (ALT-SGPT), lactate dehydrogenase (LDH), and creatinine phosphokinase (CPK). Statistically significant increases in serum levels of glucose, creatinine, AST, ALT, BUN, CPK, and LDH and significant decreases in serum levels of total protein, uric acid, cholesterol, calcium, and potassium 4 h after venom administration could be due to the toxic action of P. gravimanus venom on certain organs in rats.

Lidocaine diminishes arrhythmia by Leiurus quinquestriatus quinquestriatus venom in rats

The venom from the scorpion Leiurus quinquestriatus quinquestriatus has previously been shown to alter the excitability of the neural and skeletal muscle preparations. The present study was undertaken to explore the effects of the venom in cardiac potential signals at the animal, tissue and the cell level in rats hearts. In anaesthetised animals Leiurus quinquestriatus quinquestriatus venom (LqV) 100 microg applied intravenously reduced the heart rate by 13%, and evoked some abnormal waveforms in the electrocardiogram (ECG). Lidocaine injection (0.02 microg) restored the waveform of the ECG. However, the sinus rhythm resumed only when Atropine (2.5 microg) was applied in addition to previously administered Lidocaine. In isolated atria, LqV (10-2 mg/mL) exposure abolished the sinus rhythm and decreased the spontaneous rate by 38%, and increased the contraction amplitude by 85%, and duration of the contractions by 17%. The gross electrical activity of the preparation and the duration of the individual atrial muscle action potential were prolonged by 150% and 186%, respectively. In isolated papillary muscle, LqV evoked irregular contractions, and the duration of the action potential was increased about 15-fold. The effects by LqV in the action potential were present when calcium channels were blocked but not when extracellular sodium was substituted. Lidocaine (75 nM) antagonised the effects by LqV in isolated atria and papillary muscle. It was concluded that the lethal cardio-toxic effects by LqV were mainly due to its direct action in myocardial cells, and partly to an alteration in the autonomous nervous activity.

Use of dantrolene in experimental scorpion envenomation by Androctonus australis hector

Hyperthermia and profuse perspiration are rarely absent in severe cases of scorpion envenomation. Based on these observations, the aim of this study was to determine the therapeutic effects of dantrolene, on experimental poisoning by the venom of Androctonus australis hector. Dantrolene is a directly acting muscle relaxant which lowers the body temperature in malignant hyperthermia. The results indicate that the early use of this drug raises the LD50 in experimentally poisoned mice. If these results are transposable to humans, dantrolene could be a useful therapeutic adjuvant.

Utilization of aspirin, quinine and verapamil in the prevention and treatment of scorpion venom intoxication

Aside from serotherapy, the treatment of scorpion venom intoxication is symptomatic. The aim of this study was to compare the efficacy of drugs usually used in scorpion venom intoxications (atropine, propranolol) to that of other compounds, chosen in light of the pathophysiology of scorpion venom intoxication: dipyridamole, doxapram, quinine formate, lysine-acetyl-salicylate, valproate and verapamil. Using mice, the parameters evaluated were the preventive and therapeutic effects of drugs during experimental venom intoxication by Androctonus australis Hector and one of its toxins AaH 1, and by Buthus occitanus and Tityus serrulatus tunetanus on the other hand. It was found that although most of the drugs used could prolong the survival of the animals, the administration of verapamil and more so that of aspirin or quinine formate led to a 50 to 100% loss of venom and toxin toxicity, depending on the drug and the origin of the venom. In the case of propranolol, doxapram, atropine, dipyridamole and valproate, no or little protection were observed. If these results are confirmed in humans, the systematic use of these drugs could be a simple means for treating scorpion venom intoxication. The problem of scorpion venom intoxication poses a health problem both in the North African Maghreb and in the Americas. As a result of considerable information campaigns, the number of scorpion venom intoxications in Tunisia has dropped from 3000 in 1967 to 1000 per year in the 1980s. Serotherapy has reduced mortality to 0.35%, most deaths occurring in underweight children. In light of the large number of countries in which there is a risk of scorpion venom intoxication in the summertime, however, its prevention and treatment remain a major problem.