Influence of phentolamine and propranolol on the length of tonus and clonus in pentylenetetrazol-induced seizures in dogs.
The goal of this study was to test the hypothesis that phentolamine and propranolol premedication would affect tonus differently than clonus in pentylenetetrazol (PTZ)-induced tonic-clonic seizures in dogs. Tonic-clonic seizures were induced with IV infusion of PTZ, given as an initial 300-mg bolus and then 100-mg boluses every 10 S until a seizure began. Premedication with phentolamine (2 mg/kg of body weight) significantly shortened clonus (P less than 0.05), whereas propranolol (1 mg/kg) significantly lengthened clonus (P less than 0.05). Neither phentolamine nor propranolol significantly altered the length of tonus or the dose of PTZ required to induce seizures (P greater than 0.05). This indicates that tonus and clonus may have different neural mechanisms and that adrenergic receptors may be involved in the neural mechanisms of clonus.
D000818:Animals; D004283:Dog Diseases / Q000139:chemically induced / Q000188:drug therapy / Q000503:physiopathology*; D004285:Dogs; D005260:Female; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009129:Muscle Tonus / Q000187:drug effects; D010433:Pentylenetetrazole / Q000633:toxicity; D010646:Phentolamine / Q000494:pharmacology / Q000627:therapeutic use*; D011292:Premedication / Q000662:veterinary; D011433:Propranolol / Q000494:pharmacology / Q000627:therapeutic use*; D051381:Rats; D012640:Seizures / Q000139:chemically induced / Q000188:drug therapy / Q000503:physiopathology / Q000662:veterinary*
D011433:Propranolol; D010433:Pentylenetetrazole; D010646:Phentolamine