title: Effects of alterations in sympathetic nervous activity on the severity of reperfusion-induced arrhythmias in anaesthetised rats.
abstract: The effects of a number of interventions influencing sympathetic nervous activity on the severity of coronary artery reperfusion-induced arrhythmias in anaesthetised rats have been examined. Noradrenaline (0.1 microgram kg-1 min-1) reduced the mortality that usually occurred as a consequence of ventricular fibrillation. Isoprenaline (5 micrograms kg-1) did not significantly affect the severity of reperfusion-induced arrhythmias, although arrhythmias occurring during the 5-min period of ischaemia were exacerbated. The alpha-adrenoceptor antagonist nicergoline (0.25 and 0.5 mg kg-1 min-1) markedly suppressed both the ventricular tachycardia and fibrillation occurring upon release of the occlusion, whereas prazosin (1.0 mg kg-1) only slightly reduced the incidence of ventricular tachycardia. The beta-adrenoceptor antagonists atenolol and timolol did not significantly modify the severity of these reperfusion-induced arrhythmias. Pretreatment with reserpine (0.1 mg kg-1) or 6-hydroxydopamine (20 mg kg-1), which depleted myocardial catecholamine concentrations by 90%, had no effect on the indices of arrhythmic activity. Similarly, administration of L-thyroxine (1 mg kg-1) or propylthiouracil (50 mg kg-1) on 7 consecutive days prior to coronary artery occlusion did not alter the incidence of arrhythmias occurring upon reperfusion. Taken as a whole, these results do not suggest an important role for sympathetic nervous activity in the genesis of reperfusion-induced arrhythmias in anaesthetised rats.
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000758:Anesthesia; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D003326:Coronary Circulation; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013563:Sympathectomy, Chemical; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*; D013961:Thyroid Gland / Q000502:physiology
chemical_list: D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D007545:Isoproterenol; D009638:Norepinephrine