Effect of scorpion Leiurus quinquestriatus (H&E) venom on rat's heart rate and blood pressure.
The effects of scorpion Leiurus quinquestriatus (H&E) venom collected from the South Sinai region, Egypt, on heart rate (HR) and mean arterial pressure (MAP) were studied after intramuscular administration of 3 different doses (100, 200 and 400 micrograms/kg) to anesthetized rats. The effects of adrenergic and cholinergic blocking agents on the venom-induced HR and MAP changes were also evaluated. In two groups of rats, propranolol or atropine were given before the venom administration. In the third group the venom was given before the injection of propranolol and atropine in combination. HR was measured by using a cardiotachometer coupler connected to an ECG coupler. MAP was calculated from the recorded arterial blood pressure (ABP) after catheterization of the left common carotid artery. Venom doses of 100 and 200 micrograms/kg produced tachycardia with a dose-response relationship, whereas 400 micrograms/kg evoked sinus tachycardia followed by bradycardia then tachycardia. MAP was elevated after the administration of each dose and reached its maximum value after 60 min with a dose-response relationship. Sinus, atrial and ventricular arrhythmias were observed from the recorded ECG during the time studied. This study revealed that the venom has pressor and depressor effects which are mediated through the autonomic nervous system. Propranolol reduced the stimulatory effects of the highest dose of the venom while atropine was effective in eliminating the depressor effect of the venom on HR. The arrhythmias induced by the venom were blocked by the injection of the two blockers and are assumed to be due to the release of catecholamines and acetylcholine.
Omran
M A
MA
Pharmacology and Toxicology Department, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark 07103-2714.
Abdel-Rahman
M S
MS
Nabil
Z I
ZI
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004562:Electrocardiography / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects*; D008297:Male; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012604:Scorpion Venoms / Q000494:pharmacology*
D012604:Scorpion Venoms; D001285:Atropine; D011433:Propranolol