title: In vitro and in vivo antiarrhythmic effects of prazosin in the rat.
abstract: The possible antiarrhythmic action of prazosin was studied on two experimental models: a focus of ectopic automaticity in the rat isolated right ventricle and arrhythmias induced by i.v. CaCl2 in anaesthetized animals. In vitro, prazosin at 10(-5)M abolished the ectopic automaticity focus in 83% of cases (10/12). The effects of prazosin were not modified by reserpine pretreatment. In vivo, prazosin modified the range of CaCl2 arrhythmias, reduced the mean control sinus rate (by 21.7% at 1 mg/kg), reduced incidence and mortality by ventricular fibrillation and lengthened survival time of animals that eventually died. The results indicate that antagonism of postsynaptic alpha 1-adrenoreceptors may partly explain the efficacy of prazosin against some experimental cardiac arrhythmias.
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D002122:Calcium Chloride / Q000633:toxicity; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D011224:Prazosin / Q000627:therapeutic use*; D011799:Quinazolines / Q000627:therapeutic use*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D011799:Quinazolines; D002122:Calcium Chloride; D011224:Prazosin