title: Sex differences in susceptibility to epinephrine-induced arrhythmias.
abstract: Gender differences in incidence of cardiac arrhythmias have been documented. It is generally believed that cardiac pathology provides an arrhythmogenic substrate but that a trigger such as sympathetic nervous system activation is required to initiate arrhythmias. This study was done to determine whether there is a sex difference in susceptibility to epinephrine-induced arrhythmias in healthy rats without preexisting pathology and to determine whether gonadal hormones play a role in development of arrhythmias. Untreated, sham-operated, and gonadectomized male and female rats were anesthetized and given IV boluses of epinephrine. ECG, heart rate, and blood pressure were measured continuously for 1 minute and intermittently over a period of 30 minutes. Male rat hearts have a higher occurrence and frequency of epinephrine-induced premature ventricular contractions, missed beats, and blocks than female rat hearts. Ovariectomy increases arrhythmias, thereby abolishing the female advantage. Castration has no effect on occurrence and frequency of premature ventricular contractions but attenuates missed beats and blocks. Sex differences and effect of gonadectomy on epinephrine-induced alterations in heart rate and blood pressure implicate baroreceptor reflex in the dimorphic arrhythmogenic response. Male rat hearts are more susceptible than female hearts to epinephrine-induced arrhythmias, and gonadal hormones play a role in this disparity.
authors.affiliation: Department of Medical Surgical Nursing, University of Illinois at Chicago, and Department of Anesthesiology and Pain Management, John H. Stroger, Jr. Hospital of Cook County, Chicago, Illinois 60612, USA.
authors.forename: Linda
authors.initials: L
authors.lastname: Teplitz
authors.forename: Rajko
authors.initials: R
authors.lastname: Igić
authors.forename: Michael L
authors.initials: ML
authors.lastname: Berbaum
authors.forename: Dorie W
authors.initials: DW
authors.lastname: Schwertz
mesh_terms: D000318:Adrenergic beta-Agonists / Q000008:administration & dosage* / Q000633:toxicity; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced / Q000503:physiopathology*; D001794:Blood Pressure / Q000187:drug effects; D004195:Disease Models, Animal; D004198:Disease Susceptibility / Q000209:etiology / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000008:administration & dosage* / Q000633:toxicity; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012737:Sex Factors
chemical_list: D000318:Adrenergic beta-Agonists; D004837:Epinephrine